Hi there,
H&C - this type of application considers a variety of personal circumstances of the applicant. You can find the manual on-line and here's the link
https://www.canada.ca/en/immigratio...umanitarian-compassionate-considerations.html
In a nutshell, the decision is whether or not to waive the requirement to apply and be processed for landed immigrant status outside of Canada. In other words, if the H&C application is approved then the only hurdles to becoming a Permanent Resident are the medical and security and criminal background checks. There are no points, skills or other program requirements.
H&Cs have a fee, they do not provide the applicant with the authority to work (like a claim to Convention refugee status) and having an undecided H&C application does not prohibit the authorities from removing the applicant from Canada (if there is a removal order).
There are plenty of things that can be considered as "grounds for approval" for an H&C, however there is a cumulative consideration of the application and they refer to decisions as a "global" review - the entire sum of the evidence provided determines the success of the application.
Some major H&C considerations are: Best Interests of the Children (BIOC), Establishment in Canada, Commitment to Canada, Hardship should the person be required to apply from outside of Canada. These are some of the major items looked for, but read some of their manual for other items.
I'll mention that while "hardship" looks to be all encompassing, it isn't. Persecution under the UN Convention for Refugees isn't a part of an H&C application because there are other processes like the refugee claim that consider those things. Hardship can be natural disasters, discrimination (not rising to the level of persecution), and there are many other issues that can be raised as there is no exhaustive list with regard to hardship.
Convention Refugee Claim (CR) is an application tied directly to the United Nations definition for what personal circumstances individuals face in their country of habitual residence -
https://laws-lois.justice.gc.ca/eng/acts/i-2.5/section-96.html
There are a number of things considered here, but outside of the evidence you need to provide to substantiate your claim, this process will make a person eligible for a work permit. You will also likely receive a conditional removal order - the condition being that the order evaporates if you're determined to be a CR. If you are determined to not be a CR then the removal order becomes a concern. There is no fee for this process, unlike the H&C.
So, how does the whole Canadian process occur for most people?
Generally speaking, people come and make a refugee claim. Once it's determined that the person is eligible they can get a work permit and await the hearing to determine if the evidence provided substantiates the claim. Evidence is vitally important to the success of a claim and the general conditions within a country are not good enough (usually).
If the CR claim is refused, and if the person is eligible to apply for H&C (I believe that there is a one year bar after a negative CR claim but with an exception where there are minor children involved) then you amass a different biographical profile of your life in Canada and the perils of being deported. This is a major personal undertaking to gather letters of community support, evidence of volunteer work or other community contributions, a lack of dependence on the state for financial support, and the skies the limit for what all of this may look like and what other matters that may be raised.
This is a pretty loose look at the two processes, and I have to mention the Pre-Removal Risk Assessment (PRRA). This is another look at the Convention Refugee situation for almost anyone facing imminent removal from Canada (there's another eligibility test but this is controlled by the enforcement people). Wise applicants would wish to have both an H&C and a PRRA before the single decision-maker because it broadens their discretionary authorities. PRRA has very tight room for consideration whereas H&C has very broad discretion.
Note: a knowledgeable person could spend a very long time writing a paper to describe the ins and outs of these distinctly different processes. The thresholds for decision-making differ - H&C = balance of probabilities and CR = more than a mere possibility. In short though, Canada has very thorough process steps where failed CR claims can appeal the negative decision within the CR apparatus, and then again in the Federal Court of Canada. How deep are your pockets for legal fees? The CR question has to be fully decided before an H&C can be determined.
H&Cs require cogent, targeted submissions of evidence outlining how one meets the policies under consideration. The approval rate generally hovers above 50% but there are may, many reasons for this promising rate of approval. Successful applicants have spent years in Canada, their children are of an age where their removal would severely effect their lives. Babies, for example are less likely to be negatively effected than older children. There's a lot going on in an H&C application.
If you've made it this far through my ramble, congratulations to you! The most common approach is to make a CR claim first and hope that you don't need the tension and uncertainty of an H&C.