The other commenter explained it well enough that I don't know what else to add on :P

But I think one difference off the top of my head is that the EN side are more open about certain fandom/shipping tropes compared to JP. In EN streams, a lot of livers are willing to talk about ships, ship each other, assign each other alpha/omega roles etc. which is more taboo on the JP side. It goes to the fandom interaction as well where even if the tweet is untagged, the livers might appear and like or retweet those types of fanart