actually, I believe the rear belt is the one that's different. Although there is some debate about the front belt: the 414M2 kit gives you the TA04 frontbelt (and the 414M-specific rear belt) whereas the 414M came with both belts being 414M specific parts.
the suspension hinge pins (the longest ones holding the suspension together) are also longer than the TA04.
The two cars are by no means very similar... I'm sure I'm missing quite a bit of stuff out. If you're attempting to piece a 414M together, you might want to double-check!