Key difference: .net is a derivative of network, originally intended for organizations involved in networking technologies. Whereas, .com, derived from commercial, was originally intended for domains registered by commercial organizations.

.net and .com are generic top-level domain (gTLD) used in the Domain Name System of the Internet. Both, along with .org were created in 1985. .net is a derivative of network, and was originally intended for organizations involved in networking technologies, such as Internet service providers and other infrastructure companies. Whereas, .com, derived from commercial, was originally intended for domains registered by commercial organizations. However, the restrictions were never really enforced and were merely treated as guidelines.                        

Since the internet boom in the mid-1990s, especially the development of the World Wide Web, both have become common use. Anyone can now register a .com or .net domain, whether for business purposes or personal. .com has generally surpassed .net in  popularity and has gone on to become the most commonly used domain on the Internet. .com and .net are both currently operated by Verisign.

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