Plugged duct vs engorgement?

How do I know whether I'm engorged or have a plugged duct? More importantly, how would I handle each one? I have hardness and pain in one breast. It doesn't seem to be the whole breast, but it does seem like the hardness is growing into a larger and larger portion of my breast. I've used heat and pumped (my baby has nipple confusion and won't nurse right now), and neither has helped. The hardness seems to have expanded. No fever (not mastitis). Is this engorgement or a plugged duct? Any advice out there for how to treat it? It's been about 4 and a half hours. I've put heat on it for 5-10 mins at a time off and on over the course of an hour, and I've pumped twice now.