The InterPlanetary Name System (IPNS) part of IPFS that allows the same address to be used when content changes. This means you can give out the same address and when you change the content the address stays the same. In order to use IPNS you need to run your own local IPFS node and configure it for IPNS.
A Web3 domain essentially acts like IPNS however it is better in two main ways:
1. It makes IPFS addresses human-readable. An IPFS address for a website will look like this https://bafybeibrak77ix7gia4mlzikrxfxyfztmcu6esrdiis3x4xxld7kifwdgy.ipfs.dweb.link. An IPNS address will look similar. A Web3 domain replaces this with a readable address such as whatsweb3.x.
2. It makes updating your site easier. If you were to use IPNS you would need to run a local IPFS node on your computer, upload the new files, obtain the IPFS hash and add it to your IPNS address. You would then need to pin the hash on a pinning service so your site is available when your computer is offline. With a Web3 domain from Unstoppable Domains you just need to upload your website files and we take care of the rest.