Um, duh? That's exactly WHY they are around the same level. IF there was a difference between them, it wasn't by any substantial amount or else Piccolo, or Goku, or the Kaioshin would have informed us of such.
You're contradicting yourself here. Gotenks didn't want to kill Super Buu, but wanted to kill him? Interesting. Anyway, Gotenks couldn't even kill Buu when he Kamikaze Ghosted him into hundreds of pieces, and vaporized said remains inside the RoSaT... There's no way trying to vaporize him again would have worked.
Don't let Gotenks' arrogance and empty boasts give you a false sense of security... He wrongly assumed that he could defeat/kill Buu in every single level, lol.
You're backpedaling. At first you said they were "on par" with one another. Now you're saying they were "close to" the same level. Pick a stance and stick with it. Stop moving the goalpost, lol.
Anyway, Gohan WASN'T "close to" Buu's level at all. Again: it was an absolutely one-sided shit-stomp in Buutenks' favor(see the scans I posted earlier.)
Your main problem in these threads is that you have no grasp on what is actually canon, and are too quick to spew inaccurate 'facts' from the anime and/or non-canon scanlations.
There are NO "author-approved, Daizenshuu power levels" after the Freeza saga, btw.