'Tenure' vs. 'tenancy'
Tenure is the legal right to live in a house or use a piece of land. Tenancy is more like the occupation of a rented house. Tenure does not mean occupation by a tenant. So tenure is a right to tenancy; they are not the same, therefore they are not necessarily interchangeable; unless you are going off of the definition of tenancy meaning the right to live or work in a building that you rent. However, since you wanted them in the sense "occupation by a tenant," they are not the same.