some are actors others movie stars
Interesting question, I think its because some actors are actors. They act their roles. Gary Oldman, Anthony Hopkins, Chris Cooper, they disappear into their roles so well, we forget its them. Others are movie stars from Humphrey Bogart and Marilyn Monroe to Jim Carrey and Cameron Diaz. (just for example) Bogart used to be an actor, playing whatever roles he was given, but then when he became the good tough guy, he became a movie star. Noone wanted to see him act anymore, they wanted to see him be the good tough guy, and noone tired of that. Carrey started as a movie star,and now he wants to be an actor. Everyone wants to see a goofy rubber faced funny guy. When he tries to act, as in The Truman Show or The Majestic, noone really takes notice, because thats not what the public wants. We want Cameron Diaz to be funny and sexy. If she went all Meryl Streep on us, how would we take it? Sometimes this can backfire horribly. Pacino went from being an actor to a movie star. Now in every film we see a parody of a parody of what used to be Al Pacino hammed up by Al Pacino. HOO YAAAA!