After playing CTP for a couple of days, SMAC seems like a total clone of CivII. Everything is just renamed - energy bank=marketplace; recreation commons=temple, etc. - or split up - settler-> colony pod and former.
That's exactly what happened from Civ1 to Civ2: railroads (+50% resource) were split up into railraods, superhighways and supermarkets/farmland. City walls were split into city walls, coastal fortresses, and SAM batteries. Those were welcome improvements, but in the case of SMAC, it is hardly revolutionary, especially when this ground has been covered by MoO2, another sci-fi civ-style game that is very similar (and even includes, if my memory serves, a design-your-own units ability!)
The only new things about SMAC are the governments (which I kind of like) and the unit creation, which is only moderately useful - very infrequently do I create a unit that is not offered automatically by the computer, speeder formers being the notable excpetion because they make laying roads SOOOO easy.

But CTP is actually different. Newer. Better. Trade rocks. Stacking rocks. The visible colors rock (it's not all gray!).