"submarine" translates as "U-Boot" in German.
"atomic submarine" translates as "Atom-U-Boot"
"missile-launching submarine" translates as "Raketen-U-Boot" The newest German Boot is the "Typ 212" which uses hydrogen fuel cells that don't need air to run.
This means that the length of time they can remain submerged is far longer than any atomic submarine can. They are far safer than the atomic submarines.