I went from a well used (and abused) 2nd hand 76 CJ5 to a brand new 99 TJ. They were more different than similar.
1st gear is a lot lower so you don't need 4 lo as often, the steering is way more precise (it actually goes where you steer it), more power, FAR FAR better brakes, more comfortable seats, more room behind the seats, lower center of gravity aided by the wider track makes it far more stable on road and off road, the T-case shifts easier, the transmission shifts nicer and with better feel, it doesn't rain inside when the roof is up, the side mirrors are better positioned, the seat is lower so your head doesn't hit the roof, I guess the list is endless.
I really liked that TJ and I still kick myself sometimes for selling it after only 19 years in the seat. The only issue was the 99 didn't have antilock brakes and liked to go sideways (and quickly!) with heavy braking. I believe a 2004 will have the antilock brakes.