Difference between herpes and friction burn on penis?

I don't know where else to ask this I'm sorry! My boyfriend has something that looks like friction burn on his penis, but he's worried it's herpes. as far as I know I do not have herpes. The bumps are red but he pops them and clear stuff comes out. He says it doesn't hurt but it's been there about a week. What is the different and how can you tell.