Rent to own has few if any safeguards for the renter....because he does not have title. Typically the renter is required to put a large down payment and pay higher rent, which is applied to the purchase once the renter cleans up credit or overcomes whatever is the barrier to a traditional loan. If late on rent or late to get a loan, all is forfeited. But it depends on how the contract is written. If the seller just wants to help someone buy a property that wont sell any other way, he may offer a contract that promotes success. On a rent to own, you can probably walk away without repercussions.
Buying you lock in todays interest rate and usually have safeguards if you run into financial difficulties, like a few months to catch up on missed payments (with late fees and other fees the longer the mortgage is not paid).
It really depends on the specific property, state regulations, etc. Just make sure your contract protects you in either case. Best of luck!
As the renter in a rent-to-own situation, there should be a liquidated damages provision. The provision should be so written as to induce full performance of the contract between the parties and stipulate as to a fixed amount of liquidated damages (in the event of default by either party.)