Post your favorite J-fashion coords using bloomers / pumpkin pants!
Bloomers are like underwear. It's not supposed to be shown in public.
(I picked drawers as an example for underwear in pic related, they're essentially the same thing as bloomers just longer)
Pumpkin shorts come in many different designs but they're basically pants and meant to be worn as such, and they often feature details that show this such as belt loops, pockets, buttons, etc.
Drawers and bloomers are meant to be worn as underwear and, again, feature details that show this (mainly the elasticated waist, which may be featured in pants as well but is generally considered an "ugly" and inelegant detail which is meant for comfort more than aesthetic).
There are always exceptions to these "rules" (some pumpkin shorts look very much like bloomers and can be worn as such, for example) but that's basically it.