Clippers vs. Scissors?

my aunt cuts my hair, and she says that by using the lowest clipper setting (i think the #5 blade), it will take some of the bulk out of the sides of my hair and otherwise won't change my haircut at all. Although when my hair gets longer it does get bulky on the sides, I dont really know if what she said is true or not. Will clippering the sides bring a bad haircut; will it affect the way it grows? Is her statement true? She says it'd be perfect cuz i have thick hair, but i'm wary about trying something new. I've always had her use scissors and i dont wanna walk out with a really bad haircut.