When you’re a fireman whose job is to plan which vehicles go where or when you need to precisely specify which type of fire vehicle. Non-firemen usually say Feuerwehrfahrzeug or even Feuerwehrauto.

That’s not possible because of the way disk encryption works. When you unlock an encrypted drive, it does not actually decrypt it - that would take way too long and leave the disk unencrypted. Instead, the computer keeps the key in RAM and uses it to decrypt the accessed data blocks on the fly.