Creation of a Tenancy
The creation of a domestic tenancy may be oral or by way of a tenancy agreement or a lease. Differences between a tenancy agreement and a lease include duration and formality in execution. When the duration of the tenancy is not more than three years, a tenancy agreement is usually arranged. This will be in writing and involves a simpler method of execution. The tenancy agreement may or may not be registered. If the duration exceeds three years, a lease is required in accordance with Section 4(1) of the Conveyancing and Property Ordinance (Cap. 219). This has to be created by deed and must follow the formal procedure for a deed's execution. According to Section 3 of the Land Registration Ordinance (Cap. 128), a lease has to be registered at the Land Registry.
In practice, the solicitors who prepare the lease will submit the lease to the Land Registry for registration within one month of its execution by the landlord and tenant, in order to ensure that the priority of the lease shall commence from the date of its execution. If a lease is submitted for registration more than one month after its execution, its priority will only commence from the date of registration and not the date of its execution. A tenancy agreement is also registrable at the Land Registry. This is often done if the tenancy agreement contains a clause giving the tenant the option to renew upon its expiry.
The Land Registry -- Registration of deeds
Source : The Estate Agents Authonty