Are two modes from the same parent scale actually the same scale, just starting in a different place?
I had a student make that statement recently – that C Ionian and E Phyrgian, for example, are not different because they contain precisely the same seven notes.
What I should have said was, two humans contain roughly the same proportions of carbon, oxygen, nitrogen, hydrogen, etc. We’re made of precisely the same building blocks, but to say that that makes us the same overlooks a lot of context and specificity.
The context of an E Phrygian scale is deeply different than a C Ionian scale – it functions in different ways, it carries different meaning, and it affects the listener differently. Just as the way I live in the world is different than they way you do – even though we’re made of the same stuff.