I never knew what the difference between a blowjob and irrumatio was, also everything and everyone always considered it the same. Funny what a quick google search can do.
"Irrumatio is a form of oral sex where a man thrusts his penis into someone else's mouth, in contrast to fellatio where the penis is being actively orally excited by a fellator. The difference lies mainly in which party takes the active part."
Well, there's always something new to learn in regards of sex.
To be honest, it was only a couple years ago that I learned the clitoris it's not just "the button" (it's a larger organ, like an inverted V. The "button is just the tp, while the rest runs along with the labia. It makse a lot of sense having in mind the reactions when working those areas)
In regards to Irrumatio/Fellatio, I was being more specific, in the sense that usually a "blowjob" is throathing.
99% of sex scens involving oral and a penis, is sticking it full.
I'm not talking about being realistic of course, since even the most seasoned whore/pornstar has troubles swallowing anything bigger than 5-7 inches, I'm talking about scene variety, and of course pleasure for parties *shrug*