Lots of differences. TSI is chain driven, and found on 2008.5+ GTI's. A lot of the issues the TSI engine had, DV, cam followers etc...were addressed and fixed in the TSI engine. There is a physical list on the vortex site, and probably here, but the bottom line is the TSI is the revised and improved FSI.
The one publication I wish I could find is one listing the resistance for all the valves etc.. I know the N75 is 20 to 30 ohm and the N80 is 22 to 30 ohm, but it would be nice if all were in one publication so it were easier to look up rather than asking in a post.