How does one tell the difference between a character who is pregnant and one who has been inflated via, let's say, cum?
Especially in the case of tentacle porn (though with furries, cumming buckets tends to be literal) it seems like the two are arbitrary tags (which dealing with this specific situation) more than anything unless I'm missing something.
As a few examples, without looking at the tags already there, which ones are inflated and which are pregnant:
https://e621.net/post/show/608274
https://e621.net/post/show/653439
https://e621.net/post/show/539299
https://e621.net/post/show/652690
https://e621.net/post/show/645529

As a rule of thumb, if there isn't cum present, it's more likely to be pregnancy. It's not foolproof but it's a good starting point.

These definitely overlap, but I'd be more hesitant to tag pregnant if there's cum_inflation present without other evidence of pregnancy. For example, some characteristics are common with pregnancy such as the linea nigra across the lower abdomen and inverted belly button in post #652690 and post #539299. Generally pregnancy is also rounder like a ball rather than soft and flabby like it is in post #608274.