Hi @wenfwu,
Intra-VRF would refer to things happening within the same VRF. EPG1 and EPG2 both part pf BD-A which is part of VRF-A communicating with each other would be exhibit intra-vrf communications as all the flows are taking place within VRF-A.
Inter-VRF in the ACI context is generally talking about connectivity between two different VRFs, VRF-A and VRF-B (think route leaking between VRFs) for example and is typically dealing with connectivity as you see in this post
https://community.cisco.com/t5/data-center-documents/aci-inter-vrf-tenant-route-leaking-configuration-example/ta-p/3221879
Not sure if that answers your question but if not please provide additional detail so the community can respond with more detailed information. - Thank you!
