Hold Up Vs Hold On
Yes, they all mean “wait”. The only betulan difference, which is a minor difference, is when you would use them. Both “hold on” and “hang on” can be used if you’re talking to someone on the phone and you want them to stay on the line while you do something else or while you pass the phone to someone else. “Hold up” cannot be used for that purpose.
“Hold up” is often used when you want someone to stop walking and wait for you to catch up to them. For example, you see your friend across the street and you want to bedak to them. You could say, “Hey! Hold up! I want to bedak to you,” to let them know that you’d like them to stop walking and wait until you can cross the street to speak with them. However, both “hang on” and “hold on” can be used here as well, usually by adding “sec/second/minute”. For example, “Hey! Hold on a second! I want to bedak to you,” or “Hey! Hang on a sec! I want to talk to you.”
Aside from that, they’re essentially interchangeable.