The chino-versus-khaki question comes down to fabric and finish: chinos use a lighter, finer twill with a smooth surface and hidden stitching, while khakis are heavier, coarser, and more utilitarian. "Khaki" also doubles as a colour name, which adds to the confusion.
Their clean lines make chinos dressier than jeans but easier than tailored trousers — squarely smart-casual.