The 'Green Police' in NL (and elsewhere) were the GFP: Geheime Feldpolizei (Secret Field Police), who followed attacking, then occupying, Heer (Army) troops. Their mission was to ferret out and combat resistance, sabotage, subversion, espionage, etc. within defeated and occupied countries. They wore Heer green uniforms utilizing different, identifying piping. (Hence, 'Green Police'.) They collaborated with the SD, Gestapo, Feldgendarmerie, Heer, Abwehr and local police and intelligence operations, and possessed extraordinary powers. They were primarily a police function separate from the military, and were made up of policemen, former policemen and on-loan soldiers. They were very active in rounding up, and tracking down, downed enemy aircrew.
The Green Police Were Soilders That Would go Around Cheacking the Streets & Peoples Houses to Make Sure there Was No One Hidding there Who "Belonged in Consentrations Camps" During the Hollacust.
The Ordnungspolizei (Orpo) was the name for the uniformed regular German police force in existence during the period of Nazi Germany, notably between 1936 and 1945. It was increasingly absorbed into the Nazi police system. Owing to their green uniforms, they were also referred to as Grüne Polizei (green police). The Orpo brought together the city and municipal uniformed forces that had been organized on a state-by-state basis and covered the towns and cities, whereas the Gendarmerie (in Württemberg known as the Landjäger) covered small towns and rural areas.
The Orpo assumed duties of regular uniformed law enforcement while the SiPo consisted of the secret state police (Geheime Staatspolizei or Gestapo) and criminal investigation police (Kriminalpolizei or Kripo).