Citybus Cityflyer Airport Buses (A/E-series) vs MTR Airport Express

These are two entirely separate operators and services that get confused constantly, and the confusion costs travellers real money: MTR's Airport Express is a train, run by MTR Corporation, non-stop from Hong Kong Station or Kowloon Station to Airport Station in roughly 24 minutes. Per MTR's own fare table, the current one-way adult fare is HK$120 on Octopus (HK$130 for a paper single ticket) from Hong Kong Station, and HK$105 Octopus (HK$115 single ticket) from Kowloon Station; a same-day return using the same Octopus card costs the same as the one-way Octopus fare, and a 30-day round-trip ticket is HK$215 from Hong Kong Station or HK$195 from Kowloon Station. The old standalone 'Airport Express Travel Pass' smart card (which bundled Airport Express journeys with three days of unlimited MTR/Light Rail travel for HK$220-300) has been discontinued and no longer appears as a live product on MTR's site, so the closest currently-sold tourist bundle is the Tourist Octopus-China T-Union Card, sold with two Airport Express single-journey rides included, priced at HK$260. Citybus runs an entirely different, unrelated bus service to and from the airport, still branded Cityflyer - the name has not changed, despite the past confusion with MTR's 'Express' naming. Cityflyer buses are ordinary double-deckers that share the road, run on numbered A-series and E-series routes, and cost dramatically less: per Citybus's own route-fare tables, route A11 (North Point Ferry Pier, via Causeway Bay/Central, to the airport) is HK$40 one-way with an approximately 80-minute journey; route A21 (Hung Hom Station, via Mong Kok, to the airport) is HK$33 one-way with an approximately 78-minute journey. The E-series routes are cheaper still but serve SkyCity/AsiaWorld-Expo next to the airport rather than the terminal forecourt directly, requiring a short walk or shuttle: E11 (from Tin Hau Station) is HK$21, and E21 (from Tai Kok Tsui) is HK$14. That means the fare gap between the cheapest bus option and the Airport Express is roughly HK$100-115 one-way, for a bus journey that typically takes about three times as long and is subject to Hong Kong's often-heavy road traffic, especially around the Hong Kong-Zhuhai-Macao Bridge port and cross-harbour tunnels at peak times. The practical guidance is straightforward: if you're travelling off-peak, aren't on a tight connection, and are carrying one or two manageable bags, a Cityflyer route that starts near your hotel is a genuinely painless way to save HK$100 or more each way, and buses have generous underfloor luggage holds built for exactly this trip. If you're arriving during evening rush hour, have a tight connecting flight or event to reach, or are travelling with a group and heavy luggage where every extra 40 minutes compounds stress, the Airport Express's fixed 24-minute non-stop journey is worth paying the premium for - it's the one time on this list where speed, not price, should usually win.