T1 is generally slower than cable, sometimes slower than dsl, but always more reliable. The difference is upload bandwidth.

Common Download Speeds:
T1: exactly 1.54 Mb
Cable: 1.5 Mb - 5 Mb
DSL: 256 Kb - 6 Mb
T3: exactly 44.736 Mb

Common Upload Speeds:
T1: exactly 1.54 Mb
Cable: 128 Kb - 1 Mb
DSL: 128 Kb - 768 Kb
T3: exactly 44.736 Mb

These are only in my opinion. Exact speeds are dictated by one's ISP. Note that it is possible for t3 to be offered at a lower bandwidth, but 44.736 is it's specified rate. Pretty much only businesses or schools have t1, and bigger businesses/schools have t3.