So A Civil Campaign, which takes place on a distant planet in the future and Frederica, which is set in Regency England, are more alike than you'd expect. I'd actually pick up and consult the books for this comparison, but
1. I'm lazy
2. I just read them both**
3. the humor is my idea of fun, so I haven't forgotten those bits of the stories. Even though I'd stumble if someone asked me to sum up the Bujold book, because it was jammed with subplots, I did not forget that dinner scene. Nosirree.
The plots, eh, in the end they're both all about marriage. Granted the plot of Civil Campaign is more convoluted and has more characters. But there's love and courtship and the humorous scene that I'm thinking of -- Miles's disastrous dinner party--reminded me of the Lufra the Barcelona Collie scene. The way the people dealt with the physical funny bits was what mattered most.
Yup, the humor in both books is physical. A jumping dog vs. some jumping bugs and a great many offended people. But it's the characters' reactions that make us laugh and the fact that these incidents make perfect sense given the set of people (or animals) that are integral to the story.
That's when that sort of body humor doesn't entirely work for me -- when it doesn't come out of the characters or plot, it just comes out of the blue. Slapstick humor, a man falling on a banana peel, can be sort of funny. But that stuff can be masterful and wonderful when you know how that banana peel got there and when you know what the man's response is, and/or the people watching him fall respond. That's what both authors do so beautifully. The slightly sly or ironic responses of characters. Nothing too obvious, usually. . .yessssssss, so pretty.
** I love them both. I'd read Frederica years ago and this was an audio book. The one thing I was disappointed by on my reread --> how often Frederica calls Alverstoke "odious" Heyer's heroines spend a great deal of time berating her heroes. It's old even when they are gurgling with laughter about it. I hadn't noticed that tendency until I reread the Reluctant Widow.