That's a good question. I usually think of the Hula Grub as more of an open water, rocky point kind of bait. I use the jig & pig around cover. I don't know why other than the football head would tend to get hung up in cover. I fish the Hula Grub with a heavy head and drag it on the bottom. The J&P I tend to pitch into cover, pop it a time or two and try again.
BTW, I have sworn off any kind of plastic pig. When I use real pig ie. Uncle Josh or Strike King, I catch fish, when I don't.....I don't.
Harpo