What are the differences between tech trees?

For instance, Drengin have weaker manufacturing buildings...but they also have a big military production boost so they are better at churning out ships but weaker at building up their colonies. Iridium has better trade techs earlier. 

  Altarian has a building that benefits from both manu and research resource / adjacency bonus.  Really nice on a +3 / +1 surrounded by both types of buildings.