Hi Jenny, I just checked my copy of Francis Ching's "A Visual Dictionary of Architecture" and here are the definitions:

shade: the part s of a solid that receive no light because they are tangent to or turned away from a theoretical light source

shadow: a dark figure cast upon a surface by an opaque body intercepting the rays from a theoretical light souce

So I would venture to guess that "ombra propria" would be shade, as no object is actually casting this "darkness" and it's due to the fact that no light is falling on it.
Ombra portata would thus be the "darkness" created because something is blocking the light.

Hope that's clear! I'll do a little more digging.
Catherine