The differences between the .com, .net, and .org extensions of a domain name are primarily historical.
.com stands for "commercial," and was originally intended for use by commercial organizations.
.net stands for "network," and was originally intended for use by internet service providers and infrastructure companies.
.org stands for "organization," and was originally intended for use by non-profit organizations and other community groups.
However, in modern times, there is no strict guideline as to which type of organization should use which extension. .com, .net, and .org are all available to anyone, and which one you choose often depends on personal preference or the availability of the specific domain name you want.
As for which one is the best option to buy for a new website, it depends on the nature of the website, the audience you're trying to reach, and your personal preference. The .com is the most common TLD and is considered to be the default for most websites. But it is also more expensive than other TLDs, if you are looking for something cheaper and more specific to your niche, you can consider .net or .org.