* 啡 (fei) is the most common and general term for brown. It's used for shades ranging from light brown to dark brown.
* 褐 (haat) is used for a darker, more reddish-brown shade. It's less common than "啡" but sometimes used for specific brown hues.
Here are some examples:
* 啡色 (fei sik) - brown color
* 啡糖 (fei tong) - brown sugar
* 褐色 (haat sik) - reddish-brown color
* 褐頭髮 (haat tou fa) - brown hair
The best way to choose the right term is to consider the specific shade of brown you're referring to. If you're unsure, "啡" is always a safe bet.