IPv6 understanding....with an edgerouter

Please forgive my lack of understanding of IPv6.

I'm (finally) migrating to an ISP that natively supports IPv6. This is Zen in the UK. They provide an ND /64 prefix and a PD /48.

Now here's where my lack of understanding comes in....or perhaps I'm comparing it incorrectly to IPv4.

What's the difference between the ND and PD in (semi) laymans terms? Is the PD allocation accessible from the internet? If so, why should I use the PD over the ND range?

I'd like to distribute IP ranges across my virtual networks on my Edgerouter, which is set up as follows:

eth0 -> PPPOE
eth1 -> a server that runs various stuff, plex, http, etc (no vlan)
eth2 -> a switch that has some work devices (on a vlan)
eth3 -> not used
eth4 -> a Unifi AP that also has various networks utilising VLANs

Currently it's a pretty standard static IPV4, NAT, and then VLANs for the various stuff.

Do I need to have the PPPOE take an IP from the ND range, then allocate PD ranges to the VLANs above and utilise DHCP to assign IPs to devices?

Or can I just manually assign ranges from the ND /64 to PPPOE and all the VLANs and not use the PD block at all?

I'm totally new to all this IPV6 stuff....help!