I am studying for MCSA and have got myself so confused. What is the difference if any?
I will tell you that one has three letters and one has eleven; Seriously, VHD stands for Virtual Hard Disk/Drive, they are one in the same. There are differences with how each vendor creates/implements them, but since your studying for the mcsa it's safe to so it's likely talking about MS technology unless the book/exam specifically says otherwise. The difference between a VHD and a physical drive is that the VHD is just a file that sits on a physical drive, but to a virtual machine appears as a physical drive. There is also software that can make a vhd appear as a physical drive to a regular workstation, enabling you to operate on it as if it were a real disk, without having to attach it to a virtual machine.
VHD is a HDD image file format, virtual disk is a device.
There are many formats for virtual HDD images and VHD is just one of them (VirtualBox uses VDI, VMware has VMDK etc.). These are images, not devices.
Virtual disk is a device that doesn't exist physically, so an emulated (or virtualised) HDD, CD-ROM or something like that.
In some contexts VHD and virtual disk can be synonymous, but if you're pedantic then these two are competely different things. It's like saying that JPEG is a photo - JPEG isn't a photo, it's a compression algorithm used in EXIF files that can be used to compress photos.