What's the difference between a rental agreement and a lease?

The biggest difference is the period of occupancy. A written rental agreement provides for a tenancy of a short period (often 30 days). The tenancy is automatically renewed at the end of this period unless the tenant or landlord ends it by giving written notice, typically 60 days. For these month-to-month rentals, the landlord can change the terms of the agreement with proper written notice, subject to any rent control laws. This notice is usually 60 days, but can be shorter in some states if the rent is paid weekly or bi-weekly, or if the landlord and tenant agree.

A written lease, on the other hand, gives a tenant the right to occupy a rental unit for a set term -- most often for six months or a year but sometimes longer -- if the tenant pays the rent and complies with other lease provisions. Unlike a rental agreement, when a lease expires it does not usually automatically renew itself. A tenant who stays on with the landlord's consent will generally be considered a month-to-month tenant, subject to the rental terms (such as a no pets clause) that were in the lease.

In addition, with a fixed-term lease, the landlord cannot raise the rent or change other terms of the tenancy during the lease, unless the changes are specifically provided for in the lease, or the tenant agrees.