Can someone clarify to me if there is any difference between "amount" and "change" in physics, particularly concerning differentials? I have a problem making a distinction between an amount, say an "infinitesimal area dA" (dx*dy) which is an infinitesimally small physical entity, and "change in area dA", as in if I move down a triangle on y axis, area chages, say dA/dy, for a step in dy, area *changes* by some amount.

What I'm asking is, is there a clear distinction between *amount* and *change* in physics? Surely they can't mean the same.