Permit aircraft offering much cheaper flying than certified aircraft, but you can fly both on a PPL, and get much better privileges.
The PFA permit to fly is restricted to daytime VFR in the UK. In practice agreements have been reached to give access to most of Europe without having to get specific permission.
The NPPL is restricted to daytime VFR in the UK. There is the possibility of a similar European RPPL, which will remove the restriction on UK only and replace it with Europe only.
So there are no “big advantages” to flying a PFA type on a full PPL over an NPPL.
Rod1