The 20-year-old model insists she and her 22-year-old sibling have very different looks so don't compete for the same jobs and doesn't believe anyone would draw comparisons between them if they weren't related.
She told Grazia magazine: "People compare us as though there's not enough room for both of us.
"Everyone has their own path, we're both modelling but we have really different looks.
"We hate being competitive with each other because, apart from my mom, she's my best friend.
"When people compare you all the time, it makes you start doing it too.
"But if we weren't sisters, nobody would compare us at all. It's not normal."
Bella previously described Gigi as her "best friend".
She said: "Gigi is my best friend and I love her to death.
"She's been through everything I'm going through now because she's been in the business longer.
"If I'm sad I'll call her and she always makes me happy again. She's the best, I love her."
While the Hadid sisters have historically had markedly different tastes in fashion, Bella has revealed they've increasing started to swap outfits in recent years - even if they haven't agreed to loan pieces to one another.
Happy birthday to my best friend FOR F**king LIFE!!!!!!y role model! My person. I feel so lucky every day to call you my sister. I didn't know anyone could be so generous, smart, funny, talented, hard working, artistic, loving, respectful AND beautiful all at the same damn time!!! You make me laugh until I pee and even when I don't want to smile, you are just about the only person that can make me. Every one that knows you, immediately feels the incredible energy that radiates throughout yohank you for always being yourself, nothing more and nothing less. You are my other half & I don't know what I would ever do without you. I love you with all of my heart Squeegeed
The dark-haired beauty explained: "When we were 13, she wore lots of colour and was like Malibu girl.
"But I always wore dark colours and leather. Both our styles are evolving more now. I go to her house now and she has all my stuff, we always end up sharing things.
"We share shoes, literally everything. I don't even remember giving it to her and she will completely deny everything until the death of her."
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