There are an array of technical differences when it comes to the types of acoustic guitars on the market. Some of these differences may seem negligible on paper, such as the choice between a 38-inch and a 41-inch guitar. There are, however, several important distinctions between the two that can either help or hinder players depending on their needs.
The most obvious difference between any 38-inch guitar and its 41-inch counterparts is in the length of the neck. The latter variety has a few inches to spare, so it includes a few extra frets, way up on the scale near the sound hole. Because 38-inch guitars are designed both for players with smaller hands and/or those who are just starting too learn the instrument, there really isn't much need to include those extra frets, which are both hard to reach and hard to press down on properly.
The tone difference between a 38-inch and a 41-inch acoustic is significant considering the overall similarity between the guitars. One obvious difference that is the 41-inch variety enables guitarists to play higher notes. The different body shapes also affects the tone. Although most of the extra space on a 41-inch guitar is added to the neck, the body tends to have a slightly wider base. Because of this, the tone created is deeper and more resonant. The less-wide base on the body of a 38-inch guitar is designed mostly to aid smaller players who may have trouble strumming.
Although the difference is not extreme, a 38 inch guitar is certainly lighter than a 41-inch guitar. The hardware and materials used are typically the same; it's simply the quantity of those materials that makes up the difference. This is one of the reasons why 38-inch guitars are recommended for younger guitar players or for those who have trouble lifting a normal acoustic guitar for long periods at a time. Although 38-inch models are not the lightest acoustics possible, they are easier to manage while still providing a rich tone that smaller guitars are not quite capable of.
A combination of all these factors, including size, weight and shape, results in a clear difference in overall playability. The 38-inch guitar is lighter, so it's easier to hold. The unobtrusive shape allows for easy strumming, and the smaller neck makes it easier to play the notes. Because the guitar is smaller, it tends to require thinner strings, which also makes it easier to play. Of course, those who develop their skills on a 41-inch acoustic guitar may find the other variety's lack of size a hindrance, not unlike a bus driver being asked to sit behind the wheel of a standard sized car.