Solhint differentiation is mainly its adoption and being created by a well structured team of developers that has been continuously working in Web3 space since 2016.
How is it different?
Some tools used for similar reasons could be Slither, Ethlinter, Mythrill, MythX, and probably others too. All of these tools are not doing exactly the same, but they compete in some aspect with Solhint. Some of them provide style guides, some of them make static code analysis for security checks, etc.
Solhint differentiation is mainly its adoption and being created by a well structured team of developers that has been continuously working in Web3 space since 2016.
Is it a Public Good?
Yes, it is an Open Source project widely adopted by Solidity developers.
Is it Open Source?
Yes: https://github.com/protofire/solhint
https://npmtrends.com/ethlint-vs-solhint-vs-solium