UnrealTournament and Tribes 2 are completely different animals, and their engines are therefore optimised for those differences.
UT is designed for close up, quick games of straight on person to person combat, whereas T2 is for larger scale, tactical and strategic encounters.
UT is simple, T2 complex.
UT is alot of deathmatch with a little CTF thrown in, T2 is alot of CTF with a little DM thrown in.
Comparing them directly to each other simply doesn't work, as UT's chief rivals are Quake 3, Serious Sam and the like, and for Tribes 2 it will be Halo and Planetside.