The polo shirt is an all-encompassing term for a knit shirt with a collar and placket. It is exactly the same as a golf or tennis shirt. Rene Lacoste, the great French tennis player, designed the original polo to be more comfortable. A tee, or t-shirt, is a collarless, informal shirt made from knit fabric. A T-shirt can also be made with a pocket, long or short sleeves, and come in many colors.