Here, “holiday,” and “holiday season” mean two different things.
I don’t think it’s too far of a stretch to say that between Thanksgiving and 2 January, while people do have to work, it’s sort of understood that doing the bare minimum is ok, as a sort of unspoken reward for putting up with bullshit all year long (obviously not true for every profession, but for much of corporate America, the last six weeks of the year are a time to ease up a little).
Yes, families do get together for both, of course. I suppose it depends on the family, but that would be the norm, and in between the two holidays are parties and other festive events. MrsT and I, along with a favorite nephew and niece, are going to a Christmas market tomorrow, for example.