Season 2 of Bridgerton ended with Colin publicly embarrassing Penelope, laughing at the idea of ever courting her while surrounded by his peers. From the shadows, Penelope overhears him, prompting her to cut ties with him and not respond to his letters.

In the book, there’s a similar moment, but Colin’s behavior is much less callous. He is talking to his brothers about marriage — not discussing Penelope with a random group of peers. Plus, he has a more legitimate reason for vehemently denying courting Penelope: His mother has been hassling him about getting married for months, something his brothers were knowingly poking fun at.

In the moment, Penelope doesn’t slink away, either; she defends herself. “I never asked you to marry me. And I never— I never said to anyone that I wanted you to ask me,” she tells Colin in the book.

Penelope continues, explaining how her feelings were not hurt by his pronouncement. “You are not going to marry me. There is nothing wrong with that. I am not going to marry your brother Benedict. It doesn't hurt his feelings when I announce that I am not going to marry him. Does it, Mr. Bridgerton?”

Once Benedict agrees, Penelope adds, “It's settled, then. No feelings were hurt. Now, then, if you will excuse me, gentlemen, I should like to go home.”

By the fourth installment of the Bridgerton book series, Penelope’s secret identity is still closely guarded, and Eloise has no idea that her best friend is the anonymous writer behind Whistledown.

Without Eloise knowing, the duo never falls out with each other, and there is no rift between them in the book. (When Eloise does finally find out, she doesn’t feel particularly betrayed, either, since Whistledown never insulted her or her family directly.)

Eloise and Cressida’s friendship is one of Season 3’s biggest shocks. After Netflix teased the friendship, their comments were flooded with fans’ confusion. “oh Eloise whyyy 😭,” one wrote. But this is a Shondaland-only plot point.

In the book, Eloise never feels betrayed by Penelope, so these two never have an opportunity to grow close — and Eloise certainly never chooses Cressida over her friendship with Penelope.

Cressida is also a flatter character in the book series. She’s a simple villain, and Quinn doesn’t dig into her motivations and family background to explain why she acts so poorly.

In the TV series, Penelope works with the seamstress, Genevieve Delacroix, to deliver her issues to the publisher. But in the book, the seamstress doesn’t play a part in Whistledown.

Instead, Penelope goes herself to a dangerous part of town and leaves her latest writing in a church pew to be picked up by her publisher. It’s an unsafe practice — one that Colin catches her doing about halfway through the novel.

The book’s Lady Whistledown is not quite as vicious as the TV show’s. In the novels, Whistledown never insults the Bridgertons or ruins Marina Crane by exposing her pregnancy.

Instead, she’s seen as a more benevolent gossiper. She often leaves the wallflowers and other society outcasts alone in her reports, besides the occasional fashion commentary.

The anonymous writer is much more cutthroat in the show, leading the Bridgertons and other characters to have good reason to hate her. That animosity doesn’t really show up in the book, where the main characters (like Colin, Eloise, and Lady Danbury) respect the publication — at least, somewhat.

The show paints Colin’s popularity as a recent development, brought on by his extensive travels. He seems to be putting on a bit of a show for his peers, playing the part of a womanizer without really believing it. But in the book, Colin has always been a charming crowd favorite — he doesn’t need to expend much effort to fit in.

Penelope’s type of popularity is also different in the books. In the fourth book, there’s less of a focus on a physical glow-up (though Quinn does touch on Penelope choosing more flattering colors).

Instead, Penelope’s real blossoming happens when she starts speaking her mind more. The show doesn’t capture this the same way. Penelope still seems to be awkward and bumbling in conversation even in light of her romance with Colin.

In the book, Penelope has some fears about winding up as a companion to her aging mother. While Eloise rejoices in her decision not to marry, Penelope is less content — she never rejected any proposals, after all. At the end of the day, Penelope acknowledges that she would like to be married, but she doesn’t enact a plan to find a husband.

Penelope takes more direct action in the show, enlisting Colin to help her find a match. In the show, she even gets attention from Lord Debling, an eligible (if peculiar) bachelor, prompting Colin to feel all sorts of jealousy. This never happens in the book — Penelope has no marriage prospects until Colin shows interest.

Lady Danbury takes on a much more active role in Penelope’s storyline in the book. She’s the one to encourage Penelope to speak her mind more — and she seems to have an inkling that Penelope is the one who is writing Lady Whistledown’s column.

In the show, Danbury is focused on the return of her brother and his flirtation with Violet Bridgerton. Plus, she’s tied up meddling with Will and Alice Mondrich’s new status. It doesn’t leave much opportunity to pay attention to Penelope, too.

Throughout every season of Bridgerton, the show has proven to be steamier than the books it’s based on. In Season 3, Colin has a lot of sexy moments — and even a threesome. That doesn’t happen in the novel.

Colin’s journal is another point of difference. When Penelope snoops and reads his writing in Episode 2, it’s describing a sexual encounter. In the books, his journals are full of his travels, involving long descriptions of scenery (not other people’s bodies).

Penelope has a whole other sister in the books: Felicity, her youngest sister. In fact, when Colin begins coming around to the Featherington house, her family assumes he must be interested in Felicity, not Penelope.

The confusion leads to some awkward moments, like when Portia thinks Colin is going to propose to Felicity and tries to send Penelope away for privacy. But Felicity’s character also gives Penelope an ally in her house, a sister she can connect with.

Francesca plays a large role in Season 3. The season follows her her debut and surprising romance with John Stirling. Throughout it, it’s clear that Francesca is different from her siblings. She’s much more reserved and prefers quiet companionship.

In the novel, there’s much less focus on Francesca (or the beginnings of her love story). While the show attempts to set the scene for Francesca’s future love story — which is more complicated that Season 3 might lead you to believe — the book does not venture into her life.