Question about book "Schlachtflieger" from Luftwaffe Colours

[Griffon]

The one with the Bücker on the cover is the volume that is sold.
there is no difference AFAIK, because there exists only this one volume.
difference in covers comes from the fact that the publishing houses publish news about forthcoming releases before they are even near a final layout process-just look at the Osprey website and their future releases.
they often use old covers with about the same topic to illustrate future books.

I guess the same has happened here...

so never mind the HS-129 cover, get the volume if you can, it is very nice although the topic could have easily been expanded into a 2 or even 4 part series me thinks

cheers
phil