In the latest promotional trailer for Life Of Kylie, the 20-year-old said: 'Kendall and I, I don't think we'd be friends if we weren't sisters.'
It seems their friendship is however so sturdy they have no bounds as they share everything from clothes to their underwear.
The reality television personality said: 'I let her borrow whatever she wants. She always comes through and is like: "I need an outfit please", and I'll let her borrow whatever.
'And then I go over there, and I'm like: "Kendall, I need a pair of sweats to go home", and she'll give me the most uncomfortable old underwear, the worst sweats you've ever seen and anything that's so bad and old and small. And I'm like: "You're so mean."'
Meanwhile, Kendall, who managed to forge career on the catwalk, previously admitted she hates being told she is 'jealous' of her sister.
She said: 'I hate drama so much! I've truly never been a dramatic person, not even when I was younger.