"You are living in Canada but I am living in Brazil."
Translation:Tá tú i do chónaí i gCeanada ach tá mé i mo chónaí sa Bhrasaíl.
Is there any meaning or some sort of relation behind the five main countries that do not require a definite particle in front of it?
Generally the placenames that require an article are second declension feminine nouns, which end with a slender sound. Sasana, Meiriceá, and Ceanada are all masculine nouns, and end with a broad sound. Albain, a fifth declension feminine noun, was originally the dative form of Alba, which ends with a broad sound. Éire, another fifth declension feminine noun, was Ériu in Old Irish — also ending with a broad sound.