If D&D is going the school path it needs to start describing how schools are different.
Things created with evocation and abjuration are pure magic and are subject to anti-magic, spell resistance, dispels, and disjunctions.
Things created with evocation are real, summoned from somewhere else, aand are subject to banishment and reality.
Things created with illusion are either nor real or made with shadow stuff and are subject to disbelief.
Things created with transmutation are transformations of real things and are subject to anti-magic, spell resistance, dispels, and disjunctions.