Periodic tenancy requires notice that is either equal to the length of the tenancy or agreed otherwise while tenancy at will does not have this requirement. With tenancy at will, either party can terminate the arrangement at any time.
Periodic tenancy refers to where the tenant lives at a property for successive periods until they decide to move out. The tenant agrees to pay the landlord at certain intervals detailed in a lease. The tenant has to give notice that is either equal to the length of time he/she stayed at the property or a length of time he/she and the landlord agree to. However, tenancy at will refers to when a tenant is allowed to live at a property without a formal agreement between the tenant and landlord. Both the tenant and the landlord have the right to terminate the agreement at any time, and there is no contract or lease between them. As a result the difference between a period tenancy and tenancy at will is the difference of requirements - periodic tenancy requires notice that is either equal to the length of the tenancy or agreed otherwise while tenancy at will does not.