Russian criminal law is codified in fine detail. An article of the Criminal Code is divided into parts, and each part has its own sentencing range. Moving a case from part 4 of an article to part 2 of the same article can take a sentence from fifteen years to five. Moving it to a different article can remove the custodial element entirely.
This is why the first substantive question in any case is not "did he do it" but "is this the right article and the right part". A great deal of Russian criminal defence work is about the boundary between neighbouring offences, and about the quantitative thresholds — the weight of a substance, the size of a loss — that shift a case from one part to the next.