I don't understand the duties of a groomsman. Can you help me out?
There, I've sent you a link to an information page about it. Are you able to pinpoint the differences now?
I don't know, but they are still just very different from each other and I have nothing else to say. I'm going to be one and it's scary.
I can understand if you are nervous about it. It's okay to be put in a situation you don't full understand. You can learn new things and get more comfortable with it.
I'm not sure I'm still pretty nervous about being a groomsman.
You will learn as you go on. Maybe look online or ask more people for help on what you need to do.