And for those asking why he's only got a 4 match ban. It's a 2 match ban for using abusive language, it's then doubled if there's a mention of race, religion etc and can be further increased if there's other aggravating factors. In Suarez's case, his ban was increased because of it being such a high profile incident which brought embarrassment on the FA and because of the amount of times he said it (which seemed slightly dubious to say the least).
John Terry and Chelsea are small time so it's not really a high profile incident so that's not a aggravating factor and he was only accused of insulting Ferdinand once so that too isn't a factor to increase his ban.