It has quite a different focus than phpipam, which is mostly focused on IP addresses and related information, whereas netbox covers a wider range of items.

The main area where they don't overlap is documenting physical equipment in racks, with which you can use to do some quite useful things.

e.g. document every cable connection, so it can draw the full path from one interface to a switchport through multiple layers of structure cabling/patch panels, and associate an IP address with a specific physical interface on a specific device.

Or track power draw on PSUs, and track that back to the relevant PDU/power feed to ensure it's within permitted power levels.

Needless to say, using all features can be quite time consuming!

It doesn't, but its significantly more actively developed than PhpIPAM. There are also scanning plugins you can add.