The difference is when it kicks it and for how long. Long-term disability insurance only kicks in after an elimination period (a.k.a. a waiting period). The typical elimination period is 90 days, but can be as long as 180 or 360 days depending on your policy.
A barn is an agricultural building usually located on farms and used for various purposes. In the North American area, a barn refers to structures that house livestock, including cattle and horses, as well as equipment and fodder, and often grain. As a result, the term barn is often qualified e.g. tobacco barn, dairy barn, sheep barn, potato barn.
Modern barns are more typically steel buildings. From about 1900 to 1940, many large dairy barns were built in northern USA. These commonly have gambrel or hip roofs to maximize the size of the hay loft above the dairy roof, and have become associated in the popular image of a dairy farm.