Do they acknowledge each other as boyfriend and girlfriend, or FWB? That's the main difference. If someone is going to treat you like a girlfriend/boyfriend, but refuses to call you that, then they are keeping that person around while they wait for something better. Trust me, if he's not acknowledging her as his girlfriend, he doesn't see her that way and is using her to fill the void until he finds someone else he would rather date. It doesn't matter if he holds her hand, or they don't have sex very often (which is not an indication of anything, tbh). If someone wants to be with another person, they make sure that person knows it.
"Caring is not an advantage."