To apply inland the sponsor and the applicant have to be living together in Canada. The application is processed in Canada. To apply outland, the applicant can be outside of Canada, or can be inside Canada as a visitor or on some other type of visa. The application is processed outside of Canada at the visa office responsible for the country of residence or nationality of the applicant (and sometimes in Ottawa).
Outland is generally much faster than inland. Since you are in Canada now, you could apply either way. Outland's advantages: it is faster, usually; you can appeal if the visa is refused; you can leave Canada without jeopardizing the application. Inland's advantages: the applicant can stay in Canada throughout processing - however, since you have a work permit good until 2017, you can stay anyway; you can apply for an open work permit - again, not necessary for you.