The 3560G is your "basic" 10/100/1000BaseTx with 4 SFP ports.
3560E has 2 10Gb ports. Each of these two 10Gb ports can be converted to two 1Gb SFP ports. 3560 supports dual power supply and USB port.
3560X is the newest model. The dual power supply can be "stacked" to provide power to a second unit in case of a power supply failure. Fans are detachable as well.
Read the Data Sheet for more information.