Difference between vrf_id and present_in_vrf ?

[llamafilm]

What's the difference between these 2 fields when searching for IP Addresses? In the UI, vrf_id is called "Assigned VRF".
They appear to be exactly the same, but I haven't made extensive use of VRFs in Netbox yet.

[candlerb]

The form source is here and the filter source is here, with helper function filter_present_in_vrf() here.

The difference is that present_in_vrf[_id] shows IP addresses whose assigned VRF is the selected VRF or where their assigned VRF's export target(s) matches one of the selected VRF's import targets:

        return queryset.filter(
            Q(vrf=vrf) |
            Q(vrf__export_targets__in=vrf.import_targets.all())
        )