POAP: proof of attendance
POAPs are minted when a person shows up somewhere. If you want to gate a follow-up dinner to "people who came to my last talk," POAP is perfect.
NFT: proof of ownership
NFT gating is stable identity — a wallet holds the token until it's transferred. Better for "our community members" gates.
When to combine
The best gates are hybrid: an NFT gate (your community) AND a POAP gate (previous event attendee), so you're rewarding both membership and engagement.