I suspect that the different build number is there to stop direct patching which is what the EA Steam dispute was all about. Steam blocking direct patches and deciding what and when or even if a game is patched.
Regarding build numbers, as stated on this forum the build number refers to the order in which patches are created, higher number does necessarily mean it's a newer version, 2010's latest patch has a higher build number than TS12's.
It is quite possible for Steams version which came out after the initial version, to be in advance of patches, being it was created later it may have been first to be bug fixed or maybe at the same state or close to one of the higher build number N3V versions which were done at a later date.
One way to check is look and see if the Steam version has any of the bugs that are patched, is by looking at the TS12 bugs fixed in the announcements forum, if you haven't got those problems then it doesn't need the same patches.
Regarding build numbers, as stated on this forum the build number refers to the order in which patches are created, higher number does necessarily mean it's a newer version, 2010's latest patch has a higher build number than TS12's.
It is quite possible for Steams version which came out after the initial version, to be in advance of patches, being it was created later it may have been first to be bug fixed or maybe at the same state or close to one of the higher build number N3V versions which were done at a later date.
One way to check is look and see if the Steam version has any of the bugs that are patched, is by looking at the TS12 bugs fixed in the announcements forum, if you haven't got those problems then it doesn't need the same patches.