"A shift is commonly confused with a sheath, and the two words have more in common than the way they sound. Both refer to uncomplicated-looking dresses that end somewhere around the knee. The difference is that a shift tends to be less fitted around the waist and hips. Its straight lines are sweet and waifish in a way that the sheath, with all of its body-clinging tenacity, never will be."According to Fashion 101: A Crash Course in Clothing, the sheath was so named because it straight lines resembled a knife sheath. Huh. For me, the best way to remember the difference is that a shift dress actually shifts - with the bottom having a wider skirt than the top; meanwhile, a sheath dress is narrower, with pretty much identical measurements at the bust and the knees. Here is a visual tool to help illustrate the difference:
Triangle, I was so grateful to finally learn the difference. These days I skip trying on the sheath dresses altogether (as they never fit me quite right) and to make the shift dress a staple of my business wardrobe. UPDATE! Recently, I've discovered the perfect solution for rocking a sheath dress with a curvier, bottom-heavy frame: knits! Check out this post for more ideas about how to style a sheath dress using knit pieces!