"Windows administrators who are making the jump to Linux are often disoriented by how different everything is; not just the terminology, but the way things work, including many of the same basic types of applications.
"Because the geography is so dissimilar, many of the same things exist in parallel implementations that don't look the same; the way directory services and authentication are done, for instance. In this article, I'll walk through many of the common applications and services that Windows provides and discuss their Linux equivalents..."