I already understood that, for now, the Kbin upvote not really upvote a post/comment and to do so, I need to boost it.

But, how do Lemmy (and possibly other sites from Fediverse) deal with this difference?

For example:
If I boost a Lemmy post in Kbin, it'll count as an upvote on Lemmy? Or do I need to upvote it when it's a cross-post from another Fediverse?
And how does Lemmy understand a boost in post at Kbin?
Also, if someone at Lemmy upvote my post in Kbin, it'll count as an upvote or as a boost?