First you have the difference in focal length.
Also, the maximum aperture on the 50mm is f/1.4 while the 100mm is f/2.
The 50mm is much lighter than the 100mm, where the 100mm is close to a pound and a half!
Both of the lens filter sizes are different. The 50mm is 58mm filter thread while the 100mm is a 67mm filter thread.
IQ wise, both are fantastic. Personally, I get better results with portraits on the 100mm f/2 than the 50mm f/1.4 but the 50mm is a wonderful walk-around lens on FF.
The Zeiss lineup gives great results, but takes some practice if you use AF often.
I own both, and I must say they really do have their own personalities. As far as your second question, can you be more specific?