If we still have a Superman who never lies, then his arms got tired by carrying around a van with 2-3 thugs in it, because he is still exploring gaining strenght. I guess that the Superman version from the Justice League on-going is the strongest DCnU version, obviously above the Action Comics Superman -_- and probably also above the Superman comic version, yet I don't even that version being able to compete with Black Adam, who is simply on a higher strenght / experience / ruthlessness / maybe, maybe, maybe even speed level for now.
I had the feeling that the Superman comic version is younger and weaker than the version from Justice League, and that would actually be kinda funny, since it seems that Flash from the Flash comic is more powerful than the Flash from the Justice League comic and the same applies for Batman, even for Hal Jordan, but there it's clearly a much ... more experienced version of Hal Jordan, than the Justice League version.
Judging by that it could be that Superman is in the Superman comic more experienced than in the Justice League comic and therefore probably stronger in the end, but still - to me it looks like the version in the Superman comic is still very ... new to it and it was also said that he is becoming stronger and stronger every day and Superman said that his arms got tired, while he was lifting the van for a while.
He was probably lying, since that strenght level would be very weird for him. So he maybe only said it to scare the crap out of the thugs, but then again ... Superman lying? :-7
The one in the "Superman" comic is the present day Superman; the one in JLA is almost five years before that, and it was stated that his power grows over time.
Also, i'm pretty sure the "arms getting tired" thing was him just goading the criminals. like Batman when he's holding someone over a ledge.
Batman is also dropping them from the ledge in hopes that they break their legs, or if he is really up to it, then he breaks their legs all by himself. Batman also doesn't have much problems with lying, or denying, while I can't remember ... actually I can't remember even one instance where Superman was lying to people, but then again, I'm not the greatest Superman reader there is.