Sometimes BHs will stop when you rest also. So if you lie down for a while and they go away it's a good sign it's just BHs. I had heaps of painful, often regular BHs with pg2 and was really worried about telling the difference. But when the time came I did know. I think it came down to instinct mostly, although I think there was something a bit more intense about the real thing. BTW the real thing wasn't regular for me with DS2 and my labour was too quick for them to get closer together!