Adsorption on solids - homogeneous/heterogeneous surface definition

How could we define homogeneous and heterogeneous surfaces (rigorously)?

It is among my exam questions (but I could not find any definition in my textbook or on the internet).

I would say the homogeneous surface is a surface made of one type of molecule (opposite of the heterogeneous surface). But my knowledge about surfaces is very surface (and I am surprised it is listed as an exam question) so are there any other conditions or is it enough?