Sarah Michelle Gellar shares the key to her 17-year marriage to Freddie Prinze Jr. (Exclusive)

You may not know this, but there are actually two different Sarah Michelles.

There's the one that millions of people around the world know and love -- Sarah Michelle Gellar -- who starred on "Buffy the Vampire Slayer" for seven seasons, and there's the one that significantly less people know -- Sarah Prinze -- who is mother to two adorable children and has been married to Freddie Prinze Jr. for nearly two decades now.

During a recent interview with AOL for her partnership with Colgate Optic White, Gellar explained the "two different people" that she considers herself to be, and the boundaries that she has set up through social media in recent years in order to maintain those two sides of herself.

SEE ALSO: Sarah Michelle Gellar is 'petrified' of her children getting social media: Here's why

"By being able to have a life that's separate," she said of maintaining her strong marriage for so long, despite being in the public eye. "You know, I always joke that I'm Sarah Michelle Gellar today, but when I go home, I'm Sarah Prinze. They're two different people, and Sarah Prinze has a separate life."

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Freddie Prinze Jr. and Sarah Michelle Gellar through the years
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Freddie Prinze Jr. and Sarah Michelle Gellar through the years
Actor Freddie Prinze, Jr. and his wife, actress Sarah Michelle Gellar, pose as they arrive at the launch party for In2TV, the first broadband television network on the Internet, in Beverly Hills, California March 15, 2006. In2TV available free on AOL.com will offer thousands of classic television shows such as 'Welcome Back Kotter,' 'Chico & The Man,' and 'Wonder Woman' as well as interactive features. REUTERS/Fred Prouser
Actors Freddie Prinze Jr. and Sarah Michelle Gellar snuggle during a timeout of the New York Knicks and Miami Heat NBA playoff game at Madison Square Garden in New York, May 14. MS/HB
ANAHEIM, CA - MARCH 06: In this handout image provided by Disney Parks, Sarah Michelle Gellar, Freddie Prinze Jr. and their daughter Charlotte, 3, meet Rapunzel at the all-new 'Fantasy Faire' attraction at Disneyland on March 6, 2013 in Anaheim, California.'Fantasy Faire,' which opens March 12, is an enchanting, immersive storybook world that brings Disney Princesses and their timeless tales to life. (Photo by Paul Hiffmeyer/ Disney Enterprises, Inc. via Getty Images)
Actor Freddie Prinze, Jr. and actress Sarah Michelle Gellar attend the Ninth Annual MTV Movie Awards on June 3, 2000 at Sony Pictures Studios in Culver City, California.
Actor Freddie Prinze, Jr. and actress Sarah Michelle Gellar attend the Second Annual Teen Choice Awards on August 6, 2000 at The Barker Hangar, Santa Monica Air Center in Santa Monica, California. (Photo by Ron Galella, Ltd./WireImage)
Actor Freddie Prinze, Jr. and actress Sarah Michelle Gellar attend the 'Summer Catch' Westwood Premiere on August 22, 2001 at Mann Village Theatre in Westwood, California.
Actress Sarah Michelle Gellar and actor Freddie Prinze, Jr. attend the 58th Annual Golden Globe Awards on January 21, 2001 at Beverly Hilton Hotel in Beverly Hills, California.
�2009 RAMEY PHOTO USA, Australia and South Africa rights only New York, NY, May 12, 2009. Pregnant actress Sarah Michelle Gellar on set of a HBO new TV series'The Wonderful Maladys'filming in The Upper West Side in New York. During the day her husband Freddie Prinze Jr. is visiting her on the set. The show revolves around the lives of three adult siblings who lost their parents at a young age. CG (Photo by Philip Ramey/Corbis via Getty Images)
LONDON - JULY 05: Actress Sarah Michelle Gellar and Actor Freddie Prinze Jr pose for a picture at the Hairspray Premiere at the Odeon Cinema Leicester Square on July 05, 2007 in London, England. (Photo by MJ Kim/Getty Images)
Actor Freddie Prinze, Jr. and actress Sarah Michelle Gellar attend the 'Summer Catch' Westwood Premiere on August 22, 2001 at Mann Village Theatre in Westwood, California.
UNITED STATES - OCTOBER 08: Grudge 2' Premiere at Knott's Scary Farm in Buena Park, United States on october 08, 2006 - Sarah Michelle Gellar and Freddie Prinze Jr. (Photo by Mike FANOUS/Gamma-Rapho via Getty Images)
Sarah Michelle Gellar and Freddie Prinze Jr. (Photo by E. Charbonneau/WireImage for Sony Pictures-Los Angeles)
Sarah Michelle Gellar and Freddie Prinze Jr. (Photo by Kevin Reece/WireImage)
Freddie Prinze Jr. and Sarah Michelle Gellar (Photo by SGranitz/WireImage)
Sarah Michelle Gellar and Freddie Prinze Jr. in Tommy Hilfiger (Photo by KMazur/WireImage for Tommy Hilfiger)
MATTHEW LILLARD, FREDDIE PRINZE AND SARAH MICHELLE GELLAR ANSWER QUESTIONS ON THE SET OF MOVIE SCOOBY DOO ON THE GOLD COAST. The stars of the first-ever live-action adaptation of "Scooby Doo" from left Matthew Lillard, Freddie Prinze and Sarah Michelle Gellar answer questions during a news conference on set at the Warner Roadshow Studios on the Gold Coast May 4, 2001. The film will be filmed entirely on location in Queensland and will also star British comedian Rowan Atkinson.
Sarah Michelle Gellar (L) accompanies Freddie Prinze Jnr to the premiere for Moulin Rouge at Sydney's Fox Studios May 21, 2001. The movie, starring former Sydneysider Nicole Kidman, is directed by fellow Australian Baz Luhrmann. The Sydney premiere of the movie set in 19th century Bohemian Paris, follows on from promotions in Cannes, New York and Los Angeles. WB/DL
Actress Sarah Michelle Gellar (L) and boyfriend Freddie Prinze Jr. arrive for Nickelodeon's 15th annual Kids' Choice Awards in Santa Monica, California on April 20, 2002. Gellar and Prinze Jr. were presenting Favorite Movie during the awards. REUTERS/Adrees Latif AL/HK
UNITED STATES - OCTOBER 28: Newlyweds Sarah Michelle Gellar and Freddie Prinze Jr. are on hand at Glamour Magazine's annual Women of the Year awards at the Metropolitan Museum of Art. Gellar was given an award for her success on both the small and big screen. (Photo by Richard Corkery/NY Daily News Archive via Getty Images)
Freddie Prinze, Jr. and Sarah Michelle Gellar arrive at Nickelodeon's '15th Annual Kids' Choice Awards' held at Barker Hanger, Santa Monica Airport. (Photo by Frank Trapper/Corbis via Getty Images)
399968 02: Actors Freddie Prinze Jr. And Sarah Michelle Gellar Get An Up Close Look At Natasha And Boris, Two Arctic Foxes In Seaworld San Diego's Wild Arctic Attraction January 19, 2002 In San Diego, Ca. (Photo By Getty Images)
Freddie Prinze Jr. and Sarah Michelle Gellar during 2000 MTV Movie Awards at Sony Studios in Culver City, California, United States. (Photo by Jeff Kravitz/FilmMagic, Inc)
Freddie Prinze Jr. and Sarah Michelle Gellar during 2000 MTV Movie Awards at Sony Studios in Culver City, California, United States. (Photo by Jeff Kravitz/FilmMagic, Inc)
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"I was very afraid of social media in the beginning, because I felt it was kind of intrusive and since I've realized it's actually the opposite," Gellar went on. "I can show people the little bit that I'm comfortable with, because nine out of 10 people are just fans, but I still get to have that life that's just my own, and I think that that's really important and that's why I don't overshare so that it feels special and it still feels intimate and still feels like my own."

What also helps her maintain the essential boundaries between her public and private lives is the fact that her fans -- the millions of people who follow her on Instagram and re-watch "Buffy" and so on -- respect those boundaries, giving her a rare, fully-positive experience on social media that other celebrities can only dream of having.

"I'm very lucky, and I think my fans are pretty amazing. My fans are extremely kind. I talk to other celebrities and they tell me these horror stories about what people write, and I really haven't experienced that," she explained. "I don't go in and erase negative comments -- by the way, I don't even think I know how to do that -- but I think on a whole, I've presented myself in such a transparent way and in such a ... I hate using the word 'authentic,' but it's the only word I can really use. This is who I am: I do my own social media, it's what it is, and so I really do usually just get 'thank you' more than anything else, which is the reason that you then do it. It works pretty well."

Find out more about Sarah Michelle Gellar's partnership with Colgate Optic White here.

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