Scale implies that is it a scaled down version of the real thing. In model railroading the scales are based off the width of distance between the rails, and not the locomotives like you might think. Some of the main scales used are (from largest to smallest), O, S, HO, N, and Z. O scale is a 1/4 inch scale of the real thing with the ratio being 1:48. S being 1/6 inch scale and a ratio of 1:64. HO being 1/8 inch scale and a ratio of 1:86 or 1:87, HO is described as Half-O which explains HO. N is 1/16 inch and a ratio of 1:160. Z is 1/22 inch and a ratio of 1:220. There are other derivations for a different company or style, but that is a really accurate range for each scale.
More to come! 😀