What are the main differences between a visa and a permit?

A visa and a permit both let you enter or stay in a country, but they serve different purposes.
A visa is usually a sticker or stamp in your passport that allows you to enter a country for a specific reason, like tourism, business, or study. You usually apply for it before you travel, and it often has a time limit.
A permit, on the other hand, is a document that lets you live, work, or study in a country for a longer period. You often apply for a permit after arriving with a visa, especially if you plan to stay long-term.
In short, a PNP program for Canada lets you enter, while a permit lets you stay and do certain activities legally.