Wideband and air/fuel ratio difference

Hi guys,

Someone can tell me the difference between a wideband

http://www.jegs.com/i/Auto+Meter/105/4378/10002/-1

and a air/fuel ratio

http://www.jegs.com/i/Auto+Meter/105/4375/10002/-1

This is to help me tuning my carb.

Many thanks