Short answer
Public transport between the Azores islands is limited and not always efficient; options are mainly flights and, in some cases, ferries. Flights connect the larger islands, but schedules can be sparse and weather-dependent. Ferries operate on certain routes but are seasonal and not daily. For reliable travel, plan ahead and check schedules with local operators; for specific connections, confirm with airlines and ferry companies.
General information, not legal or tax advice. Rules and amounts change: confirm with official sources.