Definition of Variation: A change or difference in condition, amount, or level, typically with certain limits
So, it's not exactly the same thing, but, the same thing? I mean Alduin is the Nordic version of Akatosh, but he's the Nord's Akatosh, so i'm guessing that he's not exactly Akatosh, but related (mainly probably by a religious standpoint.)
Don't hurt me, please, i'm just a NOVICE! Or, last time I checked on my account thing (which IDK how that whole "leveling" thing on here works) I was, and i'm also an ES Lore noob, but I looked it up and it did say he was the NORDIC variation of Akatosh, so yeah.
Akatosh is nothing more than Alessia's [censored] politicking. He came way after the originals, who are Auriel and Alduin (mer and nordic, respectively). Both early versions are anti-Mundus, with the merrish one being a "liberator" as in destroying the prison, known as Mundus, the other being a mad devourer of kalpas, which the nords see as Alduin. All three are the same god of time.
With the mer, they see him as returning them back to The Dawn (Mankar also wanted to go back to this, but used Mehrunes Dagon as the guy, as MD also wants to go back when he was the Kind Leaper Devil King, and when mer believed they were super awesome immortal gods). The nords see Alduin as a giant reset button, and see Mundus (the mortal realm) as a testing grounds to reach the higher state of being (Vivev and, if I'm right, the Yokduans also believe).
The dwemer are weird, in that they have the merrish idea, but go a step further by going beyond The Dawn and head right to the when EVERYTHING began, but not kill the world.