Nicole Kidman sees Reese Witherspoon as a "little sister".
The 50-year-old actress teamed up with the 41-year-old star to produce mini-series 'Big Little Lies' this year and they have developed a strong friendship because they are so similar.
Speaking to Red magazine, Nicole said: "We have so much in common. We both started work really young, and both our mothers were nurses and we've had similar experiences at different times of our lives - I see her as a little sister."
Both actresses own neighbouring beach houses in the Bahamas and love seeing one another on family vacations.
Nicole said: "We're actually next-door neighbours. I'm on my balcony and I'm like, 'Hi baby'."
The two stars bought the rights to 'Big Little Lies' because they were inspired to create a 'True Detective'-style show for women.
She said: "It was born out of two women going, 'Hey, where are the roles? The really cool roles? 'True Detective' was all male-driven, where's the female-driven limited series of the sane quality?
The Oscar-winning actress was in the Bahamas with husband Keith Urban and their daughters, Sunday, nine, and six-year-old Faith, when she turned 50 earlier this year and she had a wonderful "peaceful" day celebrating with them.
She said: "We did nothing much, swimming in the ocean. I don't need an enormous amount of attention - I just need my family and a gentle, peaceful day - that's fun for me."
The 'Lion' star isn't upset about getting older and she wants to "embrace "being 50.
She said: "I believe in embracing it. And not moving away from it or denying it but blurring the lines on it.
"Men get to do that, so why can't we? And there's a wisdom that comes with it, definitely. There's an equilibrium that you don't have when you're younger."