Software design is a process of problem-solving and planning to make software.
Software development is writing and maintaining source code, but more than that includes everything from the basic idea of the software to the final software in a planned process.

We can develop the software for a variety of purposes; three of the most common of them are: Resolve a specific customer needed / specific business (exclusive software), Resolving a perceived need for a set of potential users (open source and commercial software), or for personal use (for example, a scientist may write software to automate a typical task).