return journey A return journey is the journey back to base after you've delivered a courier parcel / load. This is the bit you don't get paid for, but if you're lucky you'll get a backload to give more profit.
RFP (request for proposal) When a customer is looking for a courier to undertake ongoing work, or support a big project, they'll ask for a proposal - saying how you would cover the work, what courier service levels you would promise, what courier rates you would charge, etc.
So, the customer makes a request for proposal, courier companies make the proposals, and the customer chooses which one to give the courier service contract to.
See also ITT and tender.
round trip Round trip mileage is sometimes used as a way to work out pricing, if it's not a simple one-way job. The round trip mileage is from your base (or start point) to the courier collection address, to the courier drop addresses, and back to base. If you're using round trip mileage you would probably charge it at half your normal rate (pplm).
Round trip is not the same as wait and return.