Is inadmissibility for 'serious criminality' treated differently from ordinary 'criminality'?

Yes, they are distinct categories under the Immigration and Refugee Protection Act, and the difference has real consequences beyond just labelling. Ordinary criminality generally covers a single indictable offence, or two summary conviction offences not arising from the same event, with a Canadian equivalent. Serious criminality is reserved for offences that either carry a possible maximum sentence at or above a set number of years under Canadian law, or where the actual sentence imposed passed a set threshold, regardless of how the offence was charged abroad.

The practical differences are significant. Serious criminality generally removes access to deemed rehabilitation entirely, can affect eligibility for certain appeals and other relief, and is treated more strictly across the board. Ordinary criminality still creates inadmissibility, but leaves more routes open, including the possibility of deemed rehabilitation after enough time has passed.

Because the line between the two categories depends on precise sentencing thresholds set out in the regulations, and those thresholds shouldn't be guessed at from memory or a general sense of how serious something sounds, anyone facing either finding should have their specific offence and sentence assessed against the current legal thresholds before deciding how to proceed.