A tenancy gives the tenant a legal interest in the land and property - in effect, legal ownership for the period of the tenancy. Tenancies can take several forms:
Rent Act or Regulated Tenancies - pre
Assured Tenancies
Assured Shorthold Tenancies (default)
A license is different - it gives the "tenant" permission to occupy only. The tenant therefore gains no interest in the property or land, merely a consent from the landlord to occupy for a period of time.
The grant of a license does not create an estate in land and the licensee does not gain an interest in the property, purely permission to occupy it.
Stays in Hotels, Hostels, Lodgings (letting a room in your own home) holiday lettings, employees of a business living on the premises, and some HMOs are on license agreements.