They mean bara = gay/guy oriented stories (most have buff characters)
Meanwhile BL = girl oriented stories.
No, bl means all types of Boys' Love stories. Yaoi, shounen-ai, bara, and every queer mlm stories under the bl umbrella.
Bara is primarily created by and for gay men. That's why most bara characters are more masculine, muscular, and hairy. It often contains explicit scenes, though some works focus more on romance. I'd recommend checking out the works of Tetsuzou Okadaya, Mentaiko, and Gengoroh Tagame. They're some of my favorite bara mangaka.
On the other hand, yaoi has traditionally been created by and for a female audience. That said, there are plenty of queer creators who write yaoi as well, sometimes under pen names. So while both women and some men create yaoi but majority of its audience is female. Compared to bara, yaoi characters usually have softer, more feminine features and are often designed through the female gaze. Yaoi also tends to include explicit scenes.
Then there's shounen-ai, which focuses more on romantic relationship itself and generally doesn't contain explicit content. (Ig most of you already know all of ts. I'm just explaining it for the love of the game. )
So, all of these mlm genres fall under the broader category of Boys' Love aka BL.
Not all bl is aimed at a female audience.
as much as i know BL is a gay love story