Supported Disk Image
- HDD (Parallels version 2 only)
VDI, VMDK and VHD all support dynamically allocated storage. VMDK has an additional capability of splitting the storage file into files less than 2GB each, which is useful if your file system has a small size limit.
HDD, QCOW and QED have to be dynamically allocated if created in VirtualBox.
VirtualBox supports snapshotting of all six formats.
Moving VM Between OSes or Another Virtualization Software
VDI is the native format of VirtualBox. Other virtualization software generally don’t support VDI, but it’s pretty easy to convert from VDI to another format, especially with https://linux.die.net/man/1/qemu-img.
VMDK is developed by and for VMWare, but VirtualBox and QEMU (another common virtualization software) also support it.
VHD is the native format of Microsoft Virtual PC. Windows Server 2012 introduced VHDX as the successor to VHD, but VirtualBox does not support VHDX.
HDD is a format for Parallels Desktop. Parallels specializes in virtualization for macOS. But VirtualBox only supports an old version of the HDD format (version2).
QCOW is the old original version of the QCOW format. It has been superseded by QCOW2, which VirtualBox does not support.
QED was an abandoned enhancement of QCOW2. QEMU advises against using QED