Kampfgruppe vs Gefehtsgruppe?

[Captain L.]

I found one quotation about a Gefechtsgruppe commanded by an Lt.Col. CO of a Flak Rgt.. It took part in the fighting in the East with Army Group Mitte. Maybe something like an ad hoc unit. It was not a common expression. In WW I it was used a bit more often. The size of the Gefechtsgruppe seems to vary. One passage I found is about an Unteroffizier! (Sergeant) commanding a Gefechtsgruppe of a Cavalry Division.