There is a big difference.
Powers were frequently control based, or had a control element to them. Push, pull, shift, immobilize, stun, etc.. They were often tactical manipulation, focusing on a gameboard and set piece encounters.
Spells are usually not like that.
Spells are switched out using an entirely different mechanic, regained using a different mechanic, learned using a different mechanic, resisted using a different mechanic, and even prevented through a type of immunity that functions different than it did with powers. The interaction with other classes, with multiclassing, their relationship to hit points and defenses, none of it matches well most of the time.
Spells are not the same game space as powers. It's not the same style of play, and it's not even a very similar thing. You're trying to force that square peg into a round hole, and it doesn't work.
And again, all you've done is merely assert it. I keep asking for an example, and you keep responding with "you don't get it" and then failing to actually support your claim with anything more than a re-worded blanket assertion.
And this isn't just a matter of opinion. This disagreement isn't like you saying "I like this piece of art" and me saying "I don't like it". You're making a factual claim that element X of a game occupies the same game space as element Y. That's a claim of fact - it should be provable by you if it's accurate.