I use the words "knitting bag" and "project bag" interchangeably; for me, they are the same thing. The project bag is whatever bag has my project in it, and if it happens to be a knitting project, then it is my knitting bag as well.
(Or it is when I'm discussing it here; at home they are all "yarn bags".)
At home I have a Longaberger basket that I keep my knitting in. (Called, of course, my "yarn basket".)
For bags, I have two small project bags
that have a drawstring closure and a loop with a snap so that I can secure them to my purse or other bag. In each bag I have put in dedictated scissors and tape measure. The bag either goes into a larger tote, or my basket, depending on where I am working.
I keep my WIP, yarn and pattern in there, until I need a second ball and the project no longer fits in the bag. When it gets to that point, the bag and WIP both move into a larger bag. If it gets too big for the second bag, it stays at home in my basket -- both WIP and bag -- until it is complete.
I suppose that doesn't really answer your questions, since I bought the little pouch bags specifically because they were cute
but I have found they work very well for keeping everything I need for on-the-go knitting together, easy to find, and portable.