Open Virtualization Format (OVF) is an open standard used to package and distribute virtual appliances or VMs. OVF is a standard, with hypervisors from VMware, RHEL virtualization and Virtual Box, supporting it.
OVF packages are often described as an OVF file, but it’s more of a package. An OVF package is a collection of multiple files within a directory. One file is the .ovf file, which is an XML descriptor that outlines the package’s metadata such as name, hardware requirements and references to other files within the package. Disk images and certificate files are also contained in an OVF package.
An Open Virtualization Application/Appliance (OVA) file is a single file that archives all the files that make up an OVF. An OVA is a .tar file of all the files that make up an OVF package into a single .ova file.
Which to use?
An OVA file is much easier to distribute because we only need to send a single file rather than a collection of files, yet OVF packages provide more extensibility in terms of modifying and repackaging the virtual appliances.
Use OVF while you are developing your appliance, then distribute it using OVA. The last thing I want to do is download 10 different files just to get your virtual appliance.