300 Whisper vs 300/221 fireball

[Cold]

Ok, I am looking to buy a 300 Whisper within the next week.

I have been reading about it on and off, I read alot for my job and sometimes I get sick of reading, and would like someone to tell me, whats the difference between the two? I notice that people make a point to call one x and the other y for a reason.

On Model 1's site it says 300/221 Fb, but I was told they sold 300 W barrels, so any help guys?

Im not new to AR Variants but this one I need to learn more on, so Im going to buy one ! Thanks in advance.