The expansion pack, GalCiv II: Twilight of the Arnor, will have unique technologies per civilization. This means full trees, not just a few special techs per civ.
Below are the general concepts for each.
The Terran Alliance will have more propulsion technologies than the other civilizations. Its weapons will be the most like the default tech tree. It will have a series of technologies called Stellar Defense which will enable it to be more effective in fighting within its own area. The Terran Alliance will also have additional diplomacy and economic technologies.
The Drengin will not have factory technologies. Its tech tree will be very different from the default one in that its technologies will tend to provide planetary improvements that have a significant drawback. For instance, the slave pit technologies will provide more production but will reduce the planet's influence.
The Arcean tech tree will tend to focus more on materials rather than industry and economics as we know it. Their technologies will tend to focus on making things cost less and be of higher quality.
The Altarians will have a much smaller technology tree than the other civilizations but they will be much much more expensive.
The Torians will have technologies that tend to produce low quality but high quantity products. For instance, they will have military techs that are relatively easy to get and cost very little to manufacture but are not as effective.
The Yor won't have entertainment based technologies at all or any sort of farming technologies. Instead, the Yor will have energy production centers that increase the # of Yor units on a given world which can then be divided between production areas and research areas.
The Korx will have a lot more trade technologies than the other civilizations and gain a lot more benefit from them.
The Drath will, like the Altarians, have a much smaller technology tree that costs more but gives a lot more benefit. It will differ from the Altarians in that it will have more diplomacy and influence based technologies.
The Korath tree will be very similar to the Drengin except that they will have technologies that convert flesh into energy.
The Thalan will have a very cool technology tree based on the concept of planetary improvements that do multiple things. Thalan buildings will cost more but they will be multi-functional. There won't be a specialized entertainment area or a specialized farm but instead be buildings that do both. Similarly, there won't be a research lab or a factory but instead be a "labor" area.
The Krynn will have the most alien of the technology trees (other than maybe the Yor). The Krynn are focused on the Jihad. As a result, their buildings are based on having maximum morale in order to always have maximum production levels and maximum taxation. They will have buildings and super projects that lower the cost of leasing units so that the Krynn buy things for the Jihad far more so than other civilizations and do so with relatively little penalty.