Diff. between PR and Citizenship?

[Korea2Canada]

What is the point of applying for citzenship after PR? Is it a requirement? Or, can a person have PR forever?

 

[DGT]

You can keep renewing PR if you remain in Canada and meet the residency requirements. The point of citizenship? You can vote, acquire a Canadian passport, run for office, work in the subsection of government jobs reserved for Canadian nationals and you no longer need to meet residency requirements (I.E you could move abroad for 5 years and then return to Canada without needing to reapply for PR).

 

[Sweden]

DGT pretty much gave you a complete summary, so I wont' add anything on that.
However, yes, you can remain a PR forever if you want - there is no requirement to become a citizen. In fact, in some countries you have to renounce your citizenship in order to gain a new one, so some people choose to maintain their "original" nationality, while keeping their PR status in Canada, even if they have been living in Canada for many years.
Other countries don't have an issue with double nationalities, so it's OK to obtain the canadian one, and keep the previous one.

Your choice, really.
Sweden