Hi Kana,

   There is a small difference between these 2 constructions when you use it. If you say "Eu morava no Canadá quando era criança", you'll probably tell me a story about what happened to you in that time. However, if you'd like only to say this contends, Brazilians say "Eu morei no Canadá quando era criança" and finished, I assumed that you don't necessarily say anything more about it. ;)

Hello Kana!

I will give you the differences in English but they can be used to understand the differences in Portuguese which are quite the same!

When I say: "Eu morava no Canadá quando era criança" in English, I say: "I USED TO LIVE IN CANADA AS A CHILD" - USED TO LIVE  shows the "PERIOD"  you lived in Canada -(HABITUAL ACTION IN THE PAST)

When I say: " Eu morei no Canadá quando era criança" in English I say: " I LIVED IN CANADA AS A CHILD" - LIVED in this case shows a FACT and NOT a PERIOD.

That's it!

I understood, Thanks everyone!!!!