Orthodox Christians still are required to observe a fairly rigorous Nativity Fast, starting on November 15. Fish, oil, and wine are allowed on most days until December 20, then it is more strict.
I recall that Eastern Rite Catholics are stricter than Western Catholics on fasting, but not as strict as Orthodox.
When I became Orthodox, I discovered that even though the Advent fasting is pretty strict, there is no prohibition against Christmas decorations, music, etc. in the home during Advent.
Blessed Advent to everyone no matter how you observe it!