Merriam-Websters

Wespe -- bestimmte Wespenarten
any of various small yellow-marked vespid wasps (especially genus Vespula) that commonly nest in the ground and can sting repeatedly and painfully

Entomologists present will no doubt explain this better (and correct me if I'm wrong), but as far as I know, the layperson's explanation for the difference between a yellowjacket and a wasp (or a dirtdauber) is that a wasp's body is a solid color like brown or black, whereas a yellowjacket is a little smaller and is striped yellow and black, like a bee but without the fuzz. Yellowjackets are also said to be more aggressive than ordinary wasps and to have more painful stings.

They're definitely not bees, but they're a certain type of wasp, not just any wasp. Could you say Kurz- and Langkopfwespen? Wiki in English says they're both Vespula and Dolichovespula, but the German side only seems to translate one of the two.

http://en.wikipedia.org/wiki/Yellowjacket
http://de.wikipedia.org/wiki/Kurzkopfwespen

But I'm not sure if that's specific enough, or if there are other non-yellowjacket wasps in those groups.

Have you looked in the archive (Suche in allen Foren)? I have the feeling this has already been discussed.

Anscheinend sind die Yellowjackets alle Vespinae (Gattungen Vespa, Dolichovespula, Provespa und Vespula):
http://www.evergreen.edu/ants/TESCBiota/kingd...