Mere discrepancies in particular details do not, not ordinarily, amount to misrepresentation constituting fraud.
To be grounds for a finding of inadmissibility on the grounds of misrepresentation, the false facts need to be material . . . which is about information that could influence the outcome of the application. Since there are no qualifications based on education or employment for a person sponsored as a member of the family class, the scope of discrepancies between what was reported and otherwise proven facts, about education or employment, would need to be particularly extensive, enough so to have diverted IRCC from considering or investigating some matter which is more directly related to the requirements.
Frankly, if you are asking these questions to assist searching for, in effect, a reason or excuse to make a fraud report, I'd echo the suggestion offered by
@21Goose
The motive to pursue this appears to be largely personal. That is NOT an appropriate let alone good reason.
Fraud in these situations tends to be fairly obvious to those involved. If it is not obvious, probably is NOT fraud.
I do not hesitate to encourage reporting known, actual fraud. BUT there is little to be said, other than contempt, for those who would make accusations for personal reasons.
I understand the pain, the hurt, this may have inflicted. And there is nothing admirable about someone who would do something like that. But being a bad person is not a crime. If the substance of a fraud is not obvious, again I'd echo the suggestion offered by
@21Goose . . . let it go.
By the way, if there was actual fraud the odds are the person slips up in other ways and IRCC gets on the case anyway. Not unusual for a MOC fraud perpetrator to attempt, later, to sponsor someone they were in a relationship with prior to the MOC . . . and basically document the fraud in their own submissions to IRCC. There is no statute of limitations, so even if it is years later, if IRCC comes across evidence of fraud in the PR application process they can, and often will, pursue Removal proceedings (this can happen even after the person becomes a Canadian citizen, although that is far less common).
There is no good reason to be personally vested in how it goes. Domestic relations law is the appropriate venue for litigating most of these situations, NOT immigration.