The biggest difference is ships. Terrans have big capital ships. Collectives have lots of small, powerful ships, some of which that can capture other ships in battle.
Another important thing is that terrans can explore for border planets, but collectives can`t.
Income for collectives comes through either agriculture or plundering. Terran income is either commercial, agriculture, or with the new change, industry.
If a collective wants to use a planet to build infra on, that player has to spend 5 turns to convert that planet into a similare. Terrans don`t have to do this.