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Hero
Remember, you said "for the most part A third level spell is a third level spell". That's the notion that I was inquiring about. It looks like nicely you stepped back from that over-statement with your comment below.
I'm not stepping back from that, and it's not just "my" assertion. That, too, is part of what the developers have said, with the specific possible exceptions of a few "classic" spells they say they deliberately made a little more tempting, like fireball.
I said it would imbalanced to throw wizards (or anyone else) open to the entire spell selection because of unexpected combinations of spells. And because variety can, indeed, lead to increased power.
But that doesn't change the fact that, on a one-for-one basis, yes, for the most part a 3rd-level spell is a 3rd-level spell (or at least was intended to be, possible errors in balance notwithstanding) in 5E, when it comes to overall balance.