Abstract Art is random things drawn together that can be interpreted differently per person. It can be floating objects or random lines using your imagination.

Realistic Art is drawing exactly what you see. It has be as accurate as possible with no random stuff. It takes longer to develop.

abstract art is art that is not real. in other words its just a painting with no meaning.

realistic art how ever is human figures, and represents real things.

realistic art is done realistically. for example if you are drawing a tree, you draw it the way it looks.
abrstact art is a different way of looking at things, if you just throwing some random colors of paint on paper you could call the abstract art. or it could just be a whole new way at looking at a familiar thing, like the tree. draw it a new way, and perception of the common tree. it involves imagination/creativity