In 6205, the basic number identifies a designation in the 62 series; 6310 belongs to the 63 series. They are different references, rather than two spellings of the same part. The catalog also distinguishes 6205-2RSH and 6205-2Z: both retain the 6205 base, but the final block is part of the identification to copy when requesting them.
The reference 6004/C3 has another structure: a basic number, a slash and an additional block. Record the entire marking, preserving hyphens, slashes and letters. Comparing only the start of a code can hide an execution difference. For replacement work, compare the designation with the removed part’s dimensions and its position in the machine; a front view photograph cannot supply all this information.