The Tao of IETF

The main way is the "Category: Standards Track" part at the top. There are a few different categories: Experimental, Informational, Historic, and Standards Track.

This may not be 100% accurate, but basically: Anyone can submit an Internet Draft for the Experimental or Information categories, whereas the Standards Track ones have to come through a more intensive process, an IETF working group, etc. The Standards Track ones are the ones that are technically 'standards', or which are intended to be standards.

That said, some non-Standards Track RFCs do end up getting widely implemented (such as IRC: https://tools.ietf.org/html/rfc1459 ), and an RFC being on the Standards Track doesn't necessarily mean everyone's going to implement it -- or at least not right away (such as IPv6: https://tools.ietf.org/html/rfc2460 ), so it's normally best to take a look around and see the real-world usage for the specific technology/RFC.

For a more in-depth explanation, the IETF is the best place to take a look: https://www.ietf.org/about/standards-process.html