Pex and pipe systems confusion

have got a querie here

am wanting to start out doing residential maintenance...

last time I was in action I was doing hot and colds on new builds on old rehau before it went plastic

have got pro fit grey stuff still

was wondering what's this auspex / pex all about let's say I want to go from pex to rehau RAUTITAN do I use my pex 16mm crimper on both ends of the adapter ? as this adapter has crimp rings both ends