Interesting distinctions. The War Office 1966 driver training manual distinguishes the two types as 'divided type wheel' and 'three piece wide base rim' in the diagrams, then has an each way bet in the text: 'such wheels split into two or three parts to allow for replacement of tyre or tube'.
Looking more closely at the CMP manuals and parts lists, the Ford MBF1 uses the term split rim with the drawing of the wheel, but not in the text, and in both the Chev and Ford parts lists, the wheels are described as 'split' for the various sizes.
But neither the Chev MBC1 or C2 maintenance manuals use the term. All these manuals (MBF1 and MBC1&2) describe the wheel rims in the text as two piece.
Clear as mud, eh?
Mike