The DS one is not FFT it is a completely separate title, Final Fantasy Tactics Advance (well, FFTA is for the GBA, FFTA2 is for the DS).

I don't want to come out and slag it, as just about everyone here enjoys is, but FFT is my favorite game of all time, and I don't enjoy FFTA at all. So suffice to say that while either can be enjoyable, they are not necessarily the same experience.