Sister act! Kendall Jenner flashes toned tummy in crop top while Kylie showcases her pert derriere as they prepare to party

Their family is reality television royalty. 

And Kendall and Kylie Jenner were the definition of a sister act when they attended a pal's birthday bash in downtown LA on Saturday.

The statuesque model, 19, leaned close to Kylie in a snap shared by the 18-year-old, which she captioned 'Idgaf if they were.' 

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Sister act! Kylie Jenner Instagrammed a photo of herself cuddling up to her sister Kendall Jenner during a night on the town at a pal's birthday party in downtown Los Angeles on Saturday night

Sister act! Kylie Jenner Instagrammed a photo of herself cuddling up to her sister Kendall Jenner during a night on the town at a pal's birthday party in downtown Los Angeles on Saturday night

As close as they were that night, the ladies were polar opposites when it came to their glamorous and edgy fashion sense. 

Kylie was the height of glam with her slinky white garment, which hugged her hourglass figure and flashed her long legs. 

She wrapped on a pair of beige sandals, footwear that featured straps that wove their way around her calves.

Top of the crops! Kendall looked incredible in a long-sleeved black crop top and a pair of matching trousers

Top of the crops! Kendall looked incredible in a long-sleeved black crop top and a pair of matching trousers

Strut your stuff in Balenciaga booties

Kendall Jenner is the undisputed queen of casual dressy.

The model always knows how to hit the style spot, swathing her lithe frame in second-skin jeans, ribbed knits and little statement touches like a Givenchy bag or, say, a pair of drool-worthy Balenciaga boots...

We are of course, talking about this killer footwear here. These boots feature studded detailing and remind us of the shoes that the witches in Hocus Pocus wore.

Pair these beauties with an all black look like Kendall to let the shoe POP, or style with a body con dress and a jean jacket for an edgy look.

The good news? They're available to buy now so click the link (right) to nab them at Barney's. Or, for more affordable styles, check out the lace up beauties we've lined up for you below.

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Meanwhile, Kendall was keen to show off her famously toned tummy in a long-sleeved black crop top and a matching pair of trousers. 

Her glossy strands, messily and partially piled up into a funky hairdo, seemed to hint at her low-key mood. 

Kendall appeared to keep the makeup to a minimum, rather letting her luxuriously long lashes take centre stage.   

Polar opposites: While Kylie wore a slinky white dress, her sister kept it more casual with a black crop top and trousers
Polar opposites: While Kylie wore a slinky white dress, her sister kept it more casual with a black crop top and trousers

Polar opposites: While Kylie wore a slinky white dress, her sister kept it more casual with a black crop top and trousers

Her sister went for a different approach, applying her usual healthy coat of mascara, bronzer eye shadow, eyeliner, and a coat of foundation. 

The reality star was joined by her boyfriend Tyga, and the couple posed for an Instagram photo.

'Thanks Kendall,' Kylie described the photo, appearing to refer to the 'ew' caption in the middle of the photo, which was perhaps written in by her sister.  

Going with the flow:  Tyga donned his trusty hat as he drove his girlfriend

Going with the flow:  Tyga donned his trusty hat as he drove his girlfriend

The bash was no doubt a nice change of pace for the busy sisters, who both released their own individual apps. 

Kendall was a star once more for a brand new Estee Lauder commercial advertising Double Wear Makeup To Go Liquid Compact. 

The abbreviated video received 4,500 likes within a half hour of it being posted, with some praising the ad for commenting on today's social norms. 

'Thanks Kendall': Jenner shared a photo of herself cuddling close to her boyfriend

'Thanks Kendall': Jenner shared a photo of herself cuddling close to her boyfriend

The video takes place at a party, in which everybody is more interested in their phones than the other guests.

That is until disaster strikes, when everybody's phone batteries die all at once.

Not one to be deterred by a few technical glitches however, Kendall whips out her Estee Lauder compact to touch-up her face, at the same time bringing the lights back to life and getting the party back in swing.  

In the nine months since she was named as one of Estee Lauder's newest brand ambassadors, Kendall has worked on a number of different campaigns for the beauty giant, including several video ads for its Modern Muse cosmetics and fragrance collection.

Earlier this month, the Keeping Up with the Kardashians star debuted another video for the line of beauty products, once again donning a collection of bold red fashion items, and her now-signature red lip, while walking through the streets of Manhattan before leaping onto a yellow cab.  

Total glam: The star's face was fully decked out with rosy blush, long lashes, and heaps of bronzer eye shadow

Total glam: The star's face was fully decked out with rosy blush, long lashes, and heaps of bronzer eye shadow

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