Is there a difference between a lazy eye and a strabismus?

Yes: Lazy eye (amblyopia) may occur without any evidence of strabismus.

Yes: Strabismus is the generic term for eyes that are out of alignment. A consequence of this in some cases is the popular term 'lazy eye' which indicates an eye which might drift out of alignment or an eye with lowered vision that cannot be improved (termed amblyopia). Not all lazy eyes are out of alignment but usually if the misalignment persists, one eye will become lowered in vision ('lazy').