Not really the same, married couples have a very different protection according to law. One major difference is about the wealth gains during marriage whereas everything, retirement plans, investments, capital, material etc. falls into the family heritage which, following a divorce, will have to be split between the two. And very often, the wife will be compensated for her years spent raising kids and holding the house without being able to pursue a career. None of this exists if you live in a common law relationship.