Although the words "scale" and "gauge" are often used interchangeably, many toy train manufacturers historically had little concern with depicting accurate scale. American Flyer tended to boast its closer accuracy compared to other manufacturers. The terms "O scale" and "S scale" tend to imply serious scale modeling, while the terms "O gauge" and "S gauge" tend to imply toy trains manufactured by Lionel and American Flyer, respectively. While S gauge is fairly consistent at 1:64 scale, O gauge trains represent a variety of sizes. O gauge track happens to be 1/45 the size of real-world standard gauge track, so manufacturers in Continental Europe have traditionally used 1:45 for O gauge trains. British manufacturers rounded this up to 1:43, which is seven millimeters to the foot. U.S. manufacturers rounded it down to 1:48, which is a quarter-inch to the foot. However, most engaged in a practice of selective compression in order to make the trains fit in a smaller space, causing the actual scale to vary, and numerous manufacturers produced 1:64 scale trains—the proper size for S gauge—in O gauge, especially for cost-conscious lines.
