Generally, immigrants to Canada speak either English, or French fluently, have qualifications, with experience, that are in high demand in Canada, and are wealthy enough to pay for all the forms. As over half of Canadians have a university degree, immigrants are typically very well educated.
There are many that come on family reunification visas, who may have less than these things. While they must speak either English, or French, many may not have the education, or work experience to succeed in Canada.
Refugees have a far lower test - basically, persecution in their home countries. But, they often find a new life in Canada toughest of all, lacking language, or work skills.