In principle, these are one and the same microphone. They differ in terms of age and connection plug: the original version from the 1960s was the M 201 N("N" for "low impedance", which had to be mentioned at that time) with a 3-pole DIN plug. Shortly afterwards there was a variant called the M 201 N (C), with "(C)" standing for "Cannon" (the inventor of the XLR plug). Each of these versions could be converted into the other, which is why the respective plug was in a screw socket, which protruded a little from the microphone shaft at the back.
Over time, the DIN variant was discontinued and the so-called "Tour Group" microphone series was introduced in the 1980s. The microphone was integrated into this series as the M 201 TG.
In the meantime, the XLR plug also ends flush with the microphone shaft. Apart from that, we have been building the M 201 largely unchanged technically for many years.