These are two very different things. Homeowners insurance covers your home for theft, fire, and other "disasters." If you have a mortgage, your lender will require you to have it. Frankly, unless you can afford to replace your home and everything in it, you need it! You can generally purchase additional coverage for floods and earthquakes -- both are usually excluded from standard policies.
A home warranty, on the other hand, covers when everyday things break: the air conditioner stops working; the hot water heater starts to leak; the stove dies. Check your policy, because some policies cover more than others. For a small co-pay, the home warranty company will send a trained technician to your home to fix it. You don't *have to* have one, but I recommend one for all my clients (sellers coverage is available too). They usually pay for themselves in the first couple months you own the home!