Tourist pass vs. Octopus Card in Hong Kong

No, you do not need to buy both of them in HK. Octopus card can be used all the public transport systems, such as bus, MTR and ferry as well as tram, and you can enjoy some discounts. The tourist passes’ price is fixed, which contains limited rides or days for MTR or airport express. And if the airport express travel pass get reloaded, it will function like a normal octopus card. So which to choose actually depends on your stay period and transportation options.