The youngest Kardashian sister created a slideshow presentation Monday on her Instagram story, highlighting all the ways she and her oldest sister Kourtney are similar and different.

Khloe jokes folks have been confusing her and Kourtney for years ... including the Elvis Presley impersonator who officiated Kourtney and Travis Barker's Las Vegas wedding, and more recently, the folks waiting outside the Ritz-Carlton in Manhattan.

It seems Khloe's mainly referencing the scene that played out Monday in NYC ... where a crowd was waiting for her and Kim Kardashian to climb out of their SUV and head into the Ritz ... with someone shouting, "Kourtney," as Khloe walked by.

Khloe jokingly says ... "I totally understand how we look like identical twins so this might be challenging for some but hopefully this presentation will help."

One of the major differences, Khloe says, is hair color ... she says 99% of the time Kourtney is brunette, and 99% of the time she is blonde. Khloe also points out she stands about 5'10 while Kourtney is much shorter at 5 feet, calling the height disparity a "dead giveaway."

Of course, Khloe says there are similarities too, which is why she thinks people get them confused. She says, "Kourtney is fabulous, gorgeous, hysterical so I get how people mix us up." Khloe also says Kourtney is "hot as f***" and that's another reason she thinks people "keep blending us together."

Khloe says the mix-ups happen "on a daily basis multiple times a day" ... and she says that's being conservative.