I don't know what the Evra remark was (do you?) so I am not able to compare them. That said, given that Liverpool's statement didn't refer to race, then I assume it wasn't as serious.
But that isn't my point. I've already said that I think Liverpool were wrong to raise this in the context of the Suarez decision (although, without knowing what he said, I'm not going to say that they were wrong to raise it at all).
My point is that, given that it has been raised, it does cause a problem for the FA. If they charge then they open themselves up to having to charge lots of individuals (as other posters have pointed out). If they don't charge, then they are saying some forms of abuse are acceptable whilst others are not.