other people can give you karma for various points you make, or just to boost your ego, or because you're in charge of the number one empire and they're bandwagon jumpers... you know, whatever.
TA's main thing is unique tech trees and improvements per race, making each race a little different to play as now. What else? Immense galaxy's, Gigantic was 18x18 sectors Immense is 22x22. Only thing is, the planet count is down in TA, so you get more planets form a DA Gigantic all abundant than any TA setup. Last count was about a max of 560 planets for TA with DA having about 740 to 770 or so. Important to know for score mongers . Da's economy was tighter than DLs, well TAs even tighter than that. Starting funds are down to 3000. Ummm oh yea, Terror Stars can destory a star taking everything in it's radius with it(Planets,ships. resources), but they aren't real useful unless your roleplaying it or just to see the fireworks, cause they only move one space a turn and take a lot of investment to build. A lot of other little things and maybe a big thing or two I forgot. Also if you haven't played DA since the earlier versions(1.6 or before) you might find it has changed a little as well .