I want to preface this with how my ideas of these topics have come across so far from what I’ve read and what I assume to expect when I’m about to jump into a genre:
I always (personally) defined BL as more “shounen-ai” with maybe some small bits of sex. BL to me is an actual solid plot also being told outside of a gay relationship that is developing. So, there is a storyline that takes place outside of the characters’ blossoming romance. Usually, they feel like a fiction, or maybe less relatable than you can get from lgbtq+.
If I ever start a BL that mainly focuses on sex from the start and all the way through, it feels like a yaoi and maybe we need to find a way to categorize things as such. I can be quick to drop a “yaoi” BL if I’m searching for a story to support it. So if I come across a seme/uke office scandal, it’s likely I’m not sticking around.
LGBTQ+ stories feel similar to BL but sometimes come with more in depth societal themes about sexualities, identities, preferences, individuality, etc. Characters often seem more realistic and are involved in more raw and relatable stories that seem to come from experience. If there is a gay story in LGBTQ I’m prepared to think we’re focusing on a realistic love story. Maybe even some familial, social (or political) struggles, etc. involved.
BUT, this isn’t say there aren’t LGBTQ+ stories that have fiction and hardly focus on social or political themes, but just story telling with some kickass characters being represented. Some don’t even really give a shit to jump into the romance of it all. I’ve read those too. And lgbtq+ stories often seem to include many different types of broad relationships and identities, than just one that is the main focus.
So basically, from what I’ve read so far in each category, this is what I’ve sort of come to expect.