U.S. Government WW2 produced Information posters for both German and Japanese forces. Some of the information on these was inaccurate at the time.
Below, German WW2 Luftwaffe Insignia chart amd U.S. Published Japanese Army ranks chart
Bottom row, German published charts for Heer ranks and a pre- war guide to the German customs service (Zoll)
Above Left, Post war Heer Rank Insignia chart Above right, German pre-war uniform & Rank Insignia chart for the Zoll (Customs)