DNS is the internet standard naming system. Anytime you find a host on the internet unless you're entering the IP address, your machine is using DNS (domain naming system) to find the IP address associated with the name you typed. WINS is the Windows Internet Naming Service. WINS is only used by Pre-Win2k clients as a primary method of name-lookup.
There's really a lot more technical explaination to it, but in a nutshell, WINS is for name resolution on your LAN, and DNS is for name resolution on the internet. Note that Windows 2000 domains use DNS for all name resolution (LAN and internet) for Windows 2000 and later clients. Marc Creviere