"JB format" is indeed a synonym for "file-level backups of BD games you use in the GAMES or GAMEZ folder", probably because it was the only option back then
(whether you do minimum version hacks on them is another story)
PSJB is folder rips. Some games only work if you use ISO & it's much more convenient to use ISO, I don't know why anyone would choose PSJB format now.
I know what "PSJB" is...
Ever since the original Xbox days, I've always ripped games to me harddrive, always as folder rips.
Never experienced any issues with it.
Another advantage of folder rips is one being able to delete 3D videos/additional languages to save space.
It won't be a true 1:1 backup anymore but eh, 1:1 backups of games I got I store on me server for digital archiving n what not.
Each to their own I guess.

