I may be misunderstanding you, but by "migrate to Canada via employment sponsor" do you mean get PR by employment sponsor (like in the US)?
Canadian PR works quite differently, it has several economic classes at federal level (FSW, CEC, etc.) -- many require getting a job or valid job offer from Canadian employer first. Most provinces have their PnP nomination programs. Quebec has a completely separated immigration program.
I would suggest start reading info about Express Entry (
http://www.cic.gc.ca/english/helpcentre/results-by-topic.asp?top=29) and see what program applies to you.
You can also work in Canada with work permits: the "general" procedure is to get an offer, offer of employment number, employer applies for LMIA (unless your job is LMIA exempt), and then you can apply for work permit... LMIA is a long and costly procedure, to ensure that Canadian citizens and PRs were considered before temporary foreign workers, so many employers are not willing to do.
