May i know the different from HK airport express travel pass, express travel pass and octopus pass?

Airport Express Travel Pass is an Octopus Card with either one or two Airport Express single journey(s) plus 3 consecutive days of unlimited travel on MTR (except Airport Express, East Rail Line First Class, Lo Wu and Lok Ma Chau stations).

Octopus Card is similar as the transportation smart card in other cities which can be used on the major transportations, such as bus, MTR and ferry.