Chino and khaki are used as though they name the same trouser. One originally described a cloth and the other a color, and the distinction still tracks real differences.
Khaki began as a color
Khaki entered English from a word for dust, describing a dull earth tone adopted by nineteenth-century military forces seeking an alternative to bright uniforms.
The color spread through armies because it concealed the wearer against dry terrain, and it arrived in civilian wardrobes through surplus and veteran habit.
Used strictly, khaki says nothing about the fabric or the cut, which is why khaki trousers can be found in cottons, blends and weights that share nothing but a shade.
Chino began as a cloth
Chino refers to a cotton twill originally produced for military uniform trousers, and the name is generally traced to the trade route that supplied the cloth.
The weave is a tight twill with a diagonal rib, which gives a smooth face, a firm hand and considerably more abrasion resistance than a plain weave of the same weight.
Because it names a fabric, a chino can be any color at all, and navy and olive chinos are as legitimate as tan ones despite the color association.
Construction diverged over time
Trousers sold as chinos in the American market tend toward a cleaner finish: flat front, slanted or on-seam pockets, and a slimmer leg with minimal visible stitching.
Those sold as khakis more often retain military detailing, with pleats, patch back pockets, heavier stitching and a fuller cut through the thigh.
The distinction is a convention rather than a rule, but it is consistent enough across American retailers that the two words signal different garments on a rack.
Weight determines behavior
Lightweight twills drape softly, wrinkle readily and read as more casual, while heavier twills hold a crease and stand away from the leg.
Heavier cloth also survives washing better, since the twill structure resists the abrasion that thins lighter fabric at the seat and knees.
Fabric weight explains far more about how a pair will look after a year than the price or the label does, and it is rarely stated on the tag.
Why the confusion persists
Mass-market retailers used the words interchangeably for decades, and the association of chino cloth with khaki color made the overlap natural.
Menswear writing has partially restored the distinction, but retail listings still apply both terms to the same product depending on the season.
Reading the fabric description rather than the product name is the reliable route, since the composition and weave say what the trouser actually is.