There is a difference. Laws and culture are definitely two different ideals. Laws are definite rules set by the governing body of a nation/country/location. Culture is an ideal handed down from each generation.
Often, particularly in Eastern countries, culture tends to override laws. But it is realising this bleeding through of systems which should be observed.
Religion often stakes it claim in law and very often it is the pressure of small towns to abide rather than allow a conflict where in fact religion is not a law.
Religion is a belief and a hard held one by many people. It must be considered that not everyone agrees with religious ideals and therefore religion should not be an instrument of law.
Law, on the other hand, it supposed, and I make that clear, supposed to have a secular and non-interference from other networks to cater for everyone in a community.
Law is for the whole in a community and with this in mind the rules should be to the benefit of the whole and not a few.
Culture, on the other hand is a tradition handed down from each generation either by a family or even a community and never and I mean never be considered a law.