A rental agreement provides for a tenancy of a short period (often 30 days) that is automatically renewed at the end of the period unless the tenant or landlord ends it by giving written notice. For these month-to-month rentals, the landlord can change the terms of the agreement with proper written notice. A written lease, on the other hand, gives a renter the right to occupy a rental unit for a set term -- most often for six months or a year but sometimes longer -- as long as the tenant pays the rent and complies with other lease provisions. The landlord cannot raise the rent or change other terms of the tenancy during the lease, unless the tenant agrees. 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 after a lease ends becomes a month-to-month tenant, subject to the rental terms that were in the lease.... In short way u could say..A lease use for fixed time period usually 12 monthsto 24-plus months. rental for month-to-month,,, I hope this could give u a clear views....

In England, a lease is an agreement to use a property exclusively for a specific period of time, for residential or commercial purposes. As this kind of commitment is serious, leases can be complex. A rental agreement can also mean a residential lease (like in the paragraph above). It can also relate to the short-term hire or borrowing of things like cars, machinery, office space for meetings, crockery and glasses for parties.

For everyday use by non-lawyers, they're the same. But I believe that a rental agreement is a subset of a lease. Here is a good resource for you: http://legal-dictionary.thefreedictionary.com/Lease+Agreement