I usually see veneer as a flimsy peice of wood, less than 1/8 of an inch thick. Top I see as a peice of wood thick enough to effect the tone noticably. Generally 1/4 of an inch or thicker.
Ok, thanks for the info. Let me take this one step farther - if I put a "layer" of wood on top of a body, that was 3/16", would you call that a veneer? It would be purely for cosmetic purposes, but would it affect the tone?
Actually, 3/16" WOULD already have an effect on tone, just not nearly as defined as a thicker Top such as that on a Les Paul... Tom Anderson does a good job of explaining it in the drop top section of his site (or at least he used to)