Whats the difference between :
1)Fabric-Enabled 48-Port 10/100/1000
Ethernet Module and
2)48-Port 10/100/1000 Ethernet Module
A fabric enabled line card has access to the switch fabric of the 6500 chassis. This means that the line card has a dedicated channel for communication. This can be a 20Gb or 2 x 20Gb connection.
A non-fabric enabled card does hot have a dedicated channel but shares a bus with other non-fabric enabled line cards. The shared bus is a 32Gb connection to the switch fabric.
If you have as supervisor 2 you would need an additional Switch fabric module to fully utilise fabric enabled cards such as the WS-6548-GE-TX. Without a switch fabric module the same line card would have to share the 32Gb bus.
A supervisor 720 has an inbuilt switch fabric module so you don't need a separate card.
Some fabric enabled modules ie. the 67xx modules will only work with a Sup720.