Is marital separation different from ending a marriage in Canada?

In BC, if you stop sharing a bed (which is only one factor to consider) with your "common-law" spouse with the intent to end the "marriage-like" relationship, then you might end that kind of marital relationship, and the 2 year limitation clock starts.

However, even if you "separate" from your legally married spouse, you remain married until you divorce.  Even then, there is no time limit on support claims by divorced spouses.

In BC, there is a 2-year limit on claims for division of assets & debts by all former spouses, and for support claims by common-law spouses.