?Although toy trains are often sold in both scales and gauges, the two terms are not interchangeable and have completely different meanings.
Model trains come in many different sizes, or scales and there is no one single best scale that has ever been proven to be the best overall, but there may be a best scale for your own specific needs or space requirements. Even though model or toy trains are sold in both scales and gauges, and sometimes the terms are used interchangeably, the two terms actually mean completely different things.
Gauge is a term that refers only to the distance between the outside rails of a model train track, and does not really have any relation to the size, or scale of a toy train. This means the gauge of a train is the width of the track and only trains that fit that size track will be able to run on it. A good example of toy trains sold by the gauge is the Lionel Company that has been making toy trains for over a century in the U.S. and has manufactured products in a number of different gauges in that time. Today, Lionel trains are still sold in different gauges, with the Lionel O gauge and O-27 gauge trains being the most popular. Lionel also sells slightly smaller S gauge trains and slightly larger G (for garden) gauge trains, but the gauge reference does not really indicate the scale or size of the locomotives and cars themselves.
The actual size of a toy train is indicated by its scale that shows the proportion of the miniature as related to the real, full size trains it is a “scaled-down” version of. This means instead of referring to the track size, scale refers to a measurement of the size relationship between a model train and a train in the real world. For example, a locomotive that is 1/48th the size of the real thing is called 1/48th or 1:48 scale. The term “HO Scale” is an industry abbreviation for one of the most popular scales on the market at 1:87. Going back to the Lionel example, Lionel made a lot of HO Scale trains from 1957 to 1967, and today, HO Scale is exactly half the size of the company’s popular, but larger O gauge trains. HO Scale allows model train enthusiasts to cram more tracks, trains and scenery into a smaller space than the larger O gauge train set allows because all of the components are proportionally half as large, but sometimes the smaller HO Scale trains are a bit too small and delicate for very young kids to play with. A larger scale train like Lionel’s O gauge might be a better choice for very young children.
Bigger isn't always better when it comes to model trains, and the size of the overall track layout is usually more important than the actual scale of the train. If you don't have the space for a large layout, there are many options in smaller scales that will allow even an efficiency apartment to contain a lot of track and scenery. Depending on your goals and what you want from your hobby, balancing the available space, age of your audience, and your budget will usually yield the perfect toy train set for any area.