What is the difference between an RPL and a PPL licence?
An RPL requires less training (i.e. money) but is more restricted in how far you can fly, how many passengers you can carry and how heavy the aircraft can be. You can get an endorsement to fly anywhere domestically; there is no endorsement available to fly internationally or for the other two restrictions, nor is an instrument rating available.

A PPL allows you to fly just about any small aircraft anywhere, and you can add an instrument rating as well if desired. There is still a weight limit, but it's high enough you wouldn't hit it without needing to get (at least) a commercial license anyway.

All of the training you take for an RPL will count toward a PPL, so if you start on the former and switch to the latter, you lose nothing. Or you might get an RPL first and, if you find the it too limiting, upgrade to a PPL later; the only thing you lose in that case is having to pay for twice as many tests.