All major factions have their own unique technology tree, the minor factions share a technology tree, and custom factions can use any of the technology trees. Clicking on the faction name will take you to more information about that faction, while clicking on the technology tree description will take you to the technologies of that faction.
In the Crusade and Intrigue expansions, the technology tree is no longer faction specific. Instead, different branches of the tree are present or absent based on the faction's abilities and traits. So, for example, the branch that has the Xeno Mysticism, Precursor History, and Dark Energy Research technologies is available to any faction that has the Ancient ability, not just the Altarians.
Every race has access to the basic necessities of expanding and growing their empire. Everyone has some kind of factory progression, for example, and access to colonization tech for extreme worlds. They differ in many of the details, though, and each race has one or more areas of expertise according to their general personality and proclivities.