Classic Trilogy:
Lightsabers had one those original saber hilts and a small light-rod extending out. Notice that they were long and pointed.

Prequels:
Lightsabers have a sword hilt and a bright, bigger blade. They were shorter and not as pointed as the ones in CT.

Are the sabers different just because of technology differences in the CT's time and prequel's time or is there another reason?

It's probably cause the technology difference in the 70's and 90's.

and the ones in the prequal look so much better.

Maybe the high energy being directed through them degrades the crystals over time so that they loose their sharp focus and coloration... though one would think that the Dark Lord of the Sith would keep his crystal nice and fresh, but oh well ;)