What is the difference between these except the size of them.
Both can support same Data rate and Same distance in different variants.
What is the advantages and disadvantage of one of another.
Cisco Multirate 10GBASE-ZR/-ZW and OC-192/STM-64 LR-2 XFP Module for SMF2
SFP+ modules leave more circuitry to be implemented on the host board whereas XFP or XENPACK implemented those circuitries inside the module.
Normally, you don't have to know that because you just plug the correct device in the corresponding hole
SFP+ are a little smaller, and the module can be backward compatible with 1G SFP (if device allow it, which is not so often the case)...
Technically, both can carry the same usage (it's just another way to do it), but SFP+ has clearly won the battle.
There was exactly the same diffrence between with SFP and GBIC, X2 aso
There is also probably some patents / company aso. promoting one standard or another, but I'm not sure of that .