Quick answer: Choose an AREX train at Incheon Airport by the station you need after the ride and the next departure you can actually board. Express is aimed at Seoul Station. All-Stop serves intermediate stations and may remove a transfer.
Use the maintained Express vs All-Stop guide
The full comparison is maintained in Train to Incheon Airport: AREX Express vs All-Stop Guide. It covers both the airport arrival decision and the safer trip back to the correct terminal.
- Use Seoul Station only when the final connection fits.
- Check All-Stop for Gimpo Airport, Hongik University, Digital Media City, and other intermediate stops.
- Add immigration, baggage, ticketing, walking, and luggage-transfer time before choosing a departure.
Use the official AREX website for the timetable, fare, ticket process, service notices, and terminal details on the travel day.