Is there a difference? I heard someone say "virtual hard drive", and I am assuming they meant the virtual hard drive within a virtualized operating system.
A virtual hard drive is a drive expressed in a single file. It doesn't have to have an OS on it. With Windows 7 Ultimate and Enterprise, you can boot off a VHD (which would have an OS on it); you are not running Windows virtualized, only the drive is. Instead of talking directly to the hardware, the storage driver understands how VHDs on NTFS work.
Software virtualization is the general practice. It could be running a VM on your local workstation, or it could be server-based virtualization.
There's definitely a difference. Whether what they said is what they actually meant....