Carbon and Merge are the same thing. Merge is the network Carbon is on. The only site left that is anything like pre -black Friday.
The only networks left are Revolution (thieves who dont pay) Bovada (which is so much unlike real poker it isnt even funny), Winning (5Dimes,etc...Unclear what is going on there, seems to be run by ppl who have no clue what players want but they do pay, tournys SUCKKKKKKK!!!!) and Merge....which has software that i personally cant stand.
There is also BetOnline which is an entire story all by itself, not much traffic and they seem to pay who they want to pay and screw who they want to screw ...this is apparently decided by drawing names from a hat..
To me online poker is all but dead to American players.