One was raised in New York with her father and his money, the other without both. Photo / Getty Images.
The entire world knows about Ivanka Trump. Donald Trump's eldest daughter was front and centre of her father's presidential campaign as his advisor and de-facto First Lady. But his second daughter Tiffany is more of a mystery.
It was a minor moment in an otherwise insignificant speech. At an event in Ohio last year, Donald Trump was midway through lecturing a group of labourers, engineers and "incredible carpenters" about how terrific he is, when he broke off and addressed some special guests.
"Speaking of a job well done," he said, segueing as gracefully as ever, "we have two of my daughters here today."
At this point the room may have collectively wondered who he meant.
They, like the rest of the world, know about Ivanka – the daughter he employed as his advisor and de-facto First Lady, the daughter he said he'd date if only she wasn't his daughter, the daughter whose real name, Ivana Marie Trump, is identical to her mother's – and began to applaud at first mention of her.
Then suddenly, Trump remembered something else. "And Tiffany!"
The tale of the two Trump sisters, Ivanka, 37, and 25-year-old And Tiffany (or Tiffany, as she's less commonly known) is a curious one.
The former was raised in New York with her father and his riches nearby, the other in California without him.
One had her own jewellery line, the other was named after a jewellery brand.
One markets herself as a self-made businesswoman-cum-diplomat, the other is happy to act the archetypal billionaire's daughter.
One is best friends with Chelsea Clinton, the other with Lindsay Lohan.
One was placed front and centre in every room during their father's presidential campaign, the other was so far to the side, she might as well have stood in the car park.
And now, as the UK prepares for the Trump family's state visit next week, one will be arriving on Air Force One with Daddy, but the other is already here, dining in Annabel's, shopping in Harrods, and doing things her way...
Ivanka and Tiffany. Tiffany and Ivanka. Here's all you need to know about Tiffany Trump.
To ask whether Donald has a favourite daughter would be like asking whether Fox News has a favourite political party: just listen to him.
"Let me tell you one thing," Donald told an interviewer once, "Ivanka is a great, great beauty. Every guy in the country wants to go out with my daughter."
Then the pause again. "You know I have another daughter, with Marla, named Tiffany? She's just a beautiful great kid also. But it's very separate. When you have separate wives, it's sort of… separate."
Years later, on Election Day in 2016, he said he was proud of Tiffany "to a lesser extent" than his other offspring. Lovely.
If there's a reason Donald isn't seen as being as close with Tiffany as he is with Ivanka, it could be that they were around 3,000 miles apart for most of her childhood.
Donald and Tiffany's mother, the actress Marla Maples, separated when she was four years old and divorced when she was six.
After this, Tiffany moved from New York to California, where she was raised with Maples, and mainly saw Donald and her siblings during spring break at Mar-a-Lago, the hotel he owns in Florida.
By contrast, Ivanka made it four more years (to the age of 10) before Donald divorced her mother, the Czech former model Ivana Trump, but she stayed a mere elevator ride away from their father in Trump Tower with her brothers, Don Jr and Eric.
For one very fleeting moment it seemed as if Tiffany would follow her mother into show business.
In 2011, her final year of school, she released a pop song entitled "Like a Bird", the lyrics of which ("Diamonds are so shiny/Special things I got on me") mysteriously eluded the Pulitzer committee.
In the end she paused the music and enrolled at the University of Pennsylvania, nearer her father and half-siblings, and eventually received a double major in Sociology and Urban Studies.
Later, after internships at Vogue and an eyewear company, she began attending Georgetown Law School in Washington, DC.
As for Ivanka? She had a slightly more charmed upbringing. For instance, her father once arranged for Michael Jackson to watch her dance in The Nutcracker – a memory that may have lost its glow in recent months.
Ivanka started at a girls' school in Manhattan before attending a prestigious boarding school in Connecticut, which she likened to a "prison". John F Kennedy, Glenn Close and Michael Douglas are among other former inmates.
She then attended Georgetown University before switching to the Wharton School at the University of Pennsylvania, where her brother, Don Jr, and father also studied.
She went on to be a model before definitely not using her father's connections to get ahead in business.
Ivanka has been married to mute vampire doll Jared Kushner, who now serves alongside her as a senior advisor to Donald Trump, for 11 years. Before that she'd been linked to everybody from Lance Armstrong to Topher Grace, and once dated a man named Bingo Gubelmann.
Tiffany, meanwhile, is currently in London with her boyfriend Michael Boulos, a finance student of Lebanese and French descent who was born in Texas but grew up in Nigeria – a country Tiffany's father may or may not have been thinking of when he reportedly referred to some parts of Africa as "s****ole countries" last year.
Before Boulos, Tiffany had her own turn dating a man with a preposterous name. She and Ross Mechanic broke up last year.
Before a tidy up, Tiffany Trump's Instagram feed used to feature her partying with the "Snap Pack", a group of heiresses and models who keenly displayed their wealth.
Other members included Kyra Kennedy, a daughter of Robert F Kennedy Jr, and Barron Hilton, brother of Paris.
She's also old friends with Lindsay Lohan, who Tiffany's father once mused is "probably deeply troubled and therefore great in bed", and the actress Abigail Breslin, who her father has mercifully said nothing about.
Ivanka has her own celebrity circle – or did – starting with Chelsea Clinton, whom she reportedly met through her husband a few years ago. She and Kushner are also firm friends with Hugh Jackman, whose 50th birthday party they attended last year, and it's been reported Ivanka is close with Wendi Deng, the former wife and one-time bodyguard of Rupert Murdoch.
In Ivanka's profoundly moving first book The Trump Card: Playing to Win in Work and Life, there is just one mention of her sister – Tiffany approaching Ivanka for advice about how she should ask their father for a credit card.
"All she wanted, really, was a way to enjoy some of the privileges her friends got to enjoy," Ivanka wrote.
In the end the elder of the two "suggested [her father] think about surprising Tiffany with a credit card for Christmas, with a small monthly allowance on it. Sure enough, he did just that."
The parable of that story is unclear, but it at least illustrates the fact the sisters got on. And they continue to, apparently.
Tiffany posts photographs of her with Ivanka's three children, Ivanka says things like "she's my little sister! I've been close to Tiffany her whole life, and I really love her."
And there's no reason to doubt that. But, boy, what a pair.
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