Comparison can be found on Wikipedia.
http://en.wikipedia.org/wiki/Pilot_c...es#Sport_pilot
With the light sport you only need about half the time and also you dont need a medical if you have a valid drivers license.
You can't fail a medical and then go sport pilot though.
The cost can be prohibitive for flying. Aircraft are expensive, especially if you want something that you can actually travel in and get somewhere.
Avgas is expensive, insurance is expensive, tiedown, maintenance, annual inspections, etc etc.