Hi,
They are both compressed. But the difference is:
OVF Templates: They exist in vCenter. Exporting OVF templates allows you to create virtual appliances that other users can import later. You can use the export function to distribute pre-installed software as a virtual appliance or to distribute template virtual machines to users.
OVF/OFA File: You can make the OVF or OVA file available to users who cannot access your vCenter Server inventory.
Please give kudos if you think this was helpful. Thanks in advance!