Difference between built-in private message system in ES and converse kit

Hi,

Could someone please tell me the difference between EasySocial's built-in-private message system and the "Converse Kit"?

The product information about Converse Kit is not very helpful in this question!

I'm posting this question here because, yes, you probably can't answer or ask questions in the Converse Kit forum until you buy Converse Kit.

Thanks and kind regards
V.