It's hard to explain the difference (unless you are a Joss Whedon fan), but it's the difference between the cute funniness of say, Charmed, the Thin Man dialog funniness of Bones (which I quite like), and the ultra tongue-in-cheek funniness of Buffy. Season 5 of Golden Girls gains that tongue-in-cheek edge.
For example, Rose's St. Olaf's stories, while as outrageous, become so outlandishly satirical, they catch you off guard. Here is a story from Season 3 and one from Season 5:
Rose (3.15): I remember when I was a little girl back in St. Olaf. There was this old lady who lived up the street. She never smiled. I mean, she always looked angry. The kids said she'd kill anyone who even stepped on her property. We used to call her Mean Old Lady Hickenlooper. It turns out she had no smiling muscles. I explained to her that a smile is just a frown upside down. From then on, whenever I passed by, she would stand on her head and wave . . .The first story is funny (and silly), but the second one includes a degree of wacky irony that I've only ever seen in Son Whedon.
Rose (5.1): You know, there are all sorts of things that people get that doctors can't diagnose. Gustav Lundqvist got sick from something mysterious, and he nearly died - well, he did die, in fact. Then at the cemetery, Beatrice Lundqvist, his wife, kept screaming, "He's alive! He's alive! I can hear him from the grave!" Well, everyone thought it was the hallucinations of a grieving widow, so they sedated her. But when she woke up from her sedation, she told them that he had said from the grave, "We never paid our '78 through '86 income taxes!" And his partner said, "Only Gustav would know that! He must be alive!" So, they all raced to the cemetery, and the entire town started digging like crazy, kneeling by the grave, using their hands even, dirt flying and Beatrice screaming. And when they opened that coffin, there he was...dead as a doornail. The point is, Gustav didn't die from his mysterious disease at all! He lived and recovered. The trouble is, he recovered while he was buried, so by the time they got to him, he'd died of suffocation. Another tragic aspect was, the IRS was waiting at the cemetery to arrest Gustav's partner, Bergstrom. So, Bergstrom killed himself right then and there, by grabbing the gun from Sheriff Tokqvist and shooting himself. What they did then was, since the grave was still open, and everyone was right there, and Gustav and Bergstrom had been partners, they put Bergstrom in with Gustav and had a double burial. Unfortunately, later they found out that Bergstrom wanted to be cremated.
And I've wondered, How much was Son Whedon influenced by Papa Whedon? Or does humor just run in families? Or were Papa Whedon and Son Whedon discussing Roseanne and Golden Girls over the dinner table in 1989?
Another similarity is between Son Whedon's Buffy women and the Golden Girls (whose personalities are solidified in Season 5).
For example, Rose and Willow could be aunt and niece. They are both lovable innocents who deep-down have fiercely competitive spirits. Both may blurt out surprisingly caustic thoughts when pushed.
Blanche, more than in the other seasons, gains an Anya/Cordelia say-it-like-it-is quality in her outspokenness:
Blanche (5.2): And the thing is, after all this, I've decided not to sell my book. It's too good to sell. They can publish it after I'm dead, like Vincent van Gogh.Dorothy, with her sarcasm and eye-rolling competency, and tiny Sophia, with her pointed bon mots, together make the perfect mirror to Buffy!
Dorothy: Van Gogh was a painter, Blanche.
Blanche: Whatever. It's all the same thing. We're all artists, we're all misunderstood. He cut off his hair; maybe I'll cut off mine.
Dorothy: He cut off his ear.
Blanche: [after a beat] I have too many earrings...I can trust you, Rose. You're from Minnesota. People from Minnesota are honest; they don't lie. What could you possibly find to lie about on a farm? Lots of lakes and nice pale people. Read, Rose, don't talk. [as Rose reads] I must publish a guide to go with my book: it's too full of references people could not possibly understand. It will be taught in universities.
Rose: Blanche, you are exhausted. You have to sleep.
Blanche: "To sleep, perchance to dream..." [gasps] My God, what a wonderful line! Oh! I'm getting so good, I can't stand it! I ought to write it in my book, that line. What do you think, Rose? What page are you on?
Rose: Well, to tell you the truth, Blanche, I don't understand any of this. It doesn't seem to make any sense.
Blanche: You're from Minnesota. What have you read, for God's sake? Silas Marner? Paul Bunyan? Give me back my book. This is why Hollywood won't get it, either. I won't have my words coming out of Glenn Close's mouth. I'd rather die!
I won't push my argument any further. It is, I will grant, something of a stretch. But you know, if the Whedons were writing clever 19th century French novels, there would be an entire subculture of literary analysis devoted to comparing father and son.
Maybe it is just as well they write for television.