Hello; An answer to the major "days" here in the USA is commercial. Not that I can name them all right now, but I think there is a major named "day" each month. The next one is Easter I think. Easter, Halloween, Christmas, mothers, fathers, memorial, presidents, 4th of July, veterans, and that's all I can name right now.
The big box stores have the Easter displays up. I think they went up right after the valentine day clearance. What will come up after Easter? Anyway a big commercial day pretty much each month.
The minor days are wanna be's I guess. I cannot name those. We also have named weeks and months.