The E-6B was developed in the United States by Naval Lt. Philip Dalton (1903–1941) in the late 1930s. The name comes from its original part number for the U.S Army Air Corps, before its reorganisation in June 1941. An aluminium version was made by the London Name Plate Mfg. Co. Ltd. of London and Brighton and was marked "Computer Dead Reckoning Mk. 4A Ref. No. 6B/2645" followed by the arrowhead of UK military stores. The later miniature version being a 5A.
In the case of the CRP5, the "P" stands for "Pooleys" who make it.
So as Genghis said, they are all basically the same Dalton computer with small variations depending upon the manufacturer.
Similarly, a Douglas Protractor may not be quite the same as many of the square protractors that have copied it. Look at the inner ring of numbers; in a "Douglas" protractor they go anticlockwise from North, in some copies (Pooleys and AFE) they go clockwise from South! Most pilots never notice.