A guest network is the separated WiFi network that visitors connect to. A captive portal is the web experience that can appear before the network grants normal access.
Why the distinction matters
You can have a guest network without a marketing captive portal. You can also add a third-party portal to a supported guest network to collect consented data, show terms, authenticate users or trigger marketing workflows.
Security first
The guest network should be segmented from sensitive business systems regardless of which portal software is used. Portal software is not a substitute for sound network design.
Primary sources checked: Ubiquiti captive portal docs. Pricing and features can change; confirm time-sensitive details before buying.