There are pacing differences.
But this is all arbitrary. I could break the AD&D wizard into more levels - say 3 levels for every current two levels. This would put the wizard onto an XP table more like the thief. I could then adjust the combat, save and spell tables to keep the ration of XP to spells, bonuses etc more-or-less the same. And I could drop hit dice from d4 to (say) d3, or even - at the extreme - 1 per level, plus CON.
What would that do to the narrative? Nothing that I can see. All I've done is present wizardry in more fine-grained detail.
Yes. All you've done is create more finer grained mechanical detail. Of course you haven't changed the narrative. WHY you change to a fine grained mechanical detail should be driven by the narrative (ie fluff). The why matters (beyond "balance" or math fixes). Answering the narrative "why's" leads to what mechanics you use.
Separate advancement charts weren't created for 1E "just because". There was a reason beyond "balance" or "maths". You may not care for that reason, or the reason may be poorly defined, but it was done for a reason that made sense in-the-game frame of reference.
Take material components for spells. They are there to support the fiction that wizards need them to cast spells. Thus mechanics are born to (V,S,M listing on spells) to support that fiction. If you don't imagine wizards needing material components, you don't need the mechanics. Fluff comes first.