The English language will answer your question man.
A referral is when someone passes your name along to someone else or recommends someone to you. A hobby example would be if a provider is busy that day or doesn't provide a service you're looking for she may refer you to a girl she knows who may.
A reference is a person whose name you give someone so that they can call on them to vouch for you or your character/performance. In the hobby context this is what girls are looking for here from you. Some other provider they can reach out to who has seen you before and can verify that you're not a psycho axe murderer, LE, or a thief.
This isn't really a staff question though so I'm moving this to Coed.