Landlord insurance is different from homeowners insurance. The difference is primarily based on the amount of time a tenant will be renting the property.
For example: If you decide to move to a new property from your primary residence and then rent it out, you will need to switch to a landlord policy. But if you were to retain your primary residence as a second home (but rent it out once in a while for a week or two at a time), then you may be able to keep your existing homeowners policy. If you end up taking in a tenant full time by renting out a room or guest house, then you would most likely need to have a landlord policy.
Otherwise, if you do not inform your insurance company that the use of the property has changed, future claims may be rejected. So if a tenant decides to intentionally vandalize the dwelling, you could be out of luck under the same homeowners policy since it was intended for a primary residence.