What is the difference between je me lave les mains and je lave mes mains?

je me lave les mains = this is what you do casually before eating for example (and the best of the two sentences in French)

je lave mes mains = this is grammatically correct, but you are speaking as if your hands were an object (je lave mes jouets, I wash my toys). It could be a good sentence if you are giving your hands a special cleaning treatment, to remove paint for example.

je me lave means i have a wash