Disc, CD, DVD, Blu-ray
These words are not all interchangeable. No. Not at all.
Disc is the first word. It is what each following word is. Saying “disc” means one of those formats, not a specific one though. Disc is an optical disc. [In other computing terms: Disk is a Hard Drive Disk or a Floppy Disk. Disc is also what a vinyl record is, and devolves into other fields not related to computers and data.]
CD is the next word. CD is a disc. Specifically a data disc, an Audio Disc (CD stands for Compact Disc), and sometimes other formats of media, decrepit now. CD for Audio is still going strong.
CD is not the word to use when referring to DVD or Blu-ray video content.
DVD is the next word. DVD is a disc. Specifically a data disc that can hold a lot of information and is primarily the previous generation of Video format that was sold, still is. Movies on DVD were way better than the old tapes (VHS) and this is where people go wrong. DVD is only this format of disc. DVD‘s are quite different from Blu-ray discs.
Blu-ray is the last word. Blu-ray is a massively upgraded disc from the previous generation. It can hold much more data and is able to hold movies in Full HD, 3D, or even now UHD (4K, HDR)
So yes, UHD Blu-ray is the next generation of disc, but closely related to Blu-ray, much more than Blu-ray is related to DVD.
When I read people’s reviews on products, like on Amazon, they say “CD” when talking about either DVD or Blu-ray they purchased. Or they call CD‘s they purchased “DVD” or Blu-ray will be called “DVD“.
I don’t review this very often, if I did I would stick to calling a spade a spade. I do not understand why others can’t call the format out properly.
What is it about calling all disc releases DVD. Many things are available now, language needs to be updated on many sites, companies, etc.