What is the difference between flat lashes and classic lashes? Flat lashes have a flat, oval shape, while classic lashes have a rounded base. So, flat lashes and classic lashes look like different styles. Flat lashes create a more slender eyeliner effect on the eye, while classic lashes create a very subtle, natural look. Flat lashes can only be placed at the top or bottom of your natural lashes. One of the benefits of Classic lashes, on the other hand, is that they can be placed on the top, side or bottom of the natural lashes. Flat lashes fit the Classic Lash Kit. Flat lashes are perfect for any eye and style, just like regular single lashes. But if you want thicker lashes without adding the weight of natural lashes, then flat lashes are the perfect choice.