In sociological terms, there is a difference between what is normal, and what follows the norm.
Thesocietypages.org puts it the following way:
Sociologists distinguish between the terms norm, normal, and normative.
• The norm refers to what is common or frequent. For example, celebrating Christmas is the norm in America.
• Normal is opposed to abnormal. Even though celebrating Christmas is the norm, it is not abnormal to celebrate Hanukkah. To celebrate Hanukkah is perfectly normal.
That leaves open that question of what adjective one can use to describe something as following the norm. E.g. In America, the BLANK midwinter celebration is Christmas.