Yes, they were both from December. I think what jumps out at me the most is how the 79 one tries to keep everyone together, whereas the 80 one is more comfortable using segmented groups. The attempt at a young, hip vibe in the 1980 episode, and the heavy focus on Morgan, is another noticeable difference.
I know she was apparently difficult but I love what Kristen Vigard brings to the role. She makes me feel sorry for Morgan, even in some horrible moments (like berating a pregnant woman), in a way I never could for Marland's other characters in this vein (Laura, Lily).
I do think that some years bled together, like Pam Long's Christmases in her second run, but for the most part the show just seems so different each year.