Express and all-stop are different products
The official railway distinguishes the reserved Express from the all-stop train. For Hongdae, direct station access matters more than the word ‘Express’: travelling past the useful station to Seoul Station can create an unnecessary return transfer.
Check which side of Hongik University station
The station and surrounding streets are large enough that exit choice, lift access and the final walk affect a luggage-heavy arrival. Save the accommodation address in a Korean map and identify the practical exit before leaving the airport.
When road transport deserves the comparison
An airport bus or taxi can win for a hotel far from the station, a large group, limited mobility or an arrival near the end of rail service. Confirm a live bus stop and schedule; do not treat a generic Hongdae label as door-to-door coverage.