A knowledge base article about What's the difference between a YubiKey and a Simple Hardware Token? provided by the UC Berkeley IT Service Hub - Knowledge Portal
To use a YubiKey, once you’ve inserted it into a USB port, you can touch your YubiKey and it will automatically generate a code and complete the 2-Step. (See this page for images) To use a simple hardware token, you will need to manually type in the code that it generates. (See this page for images).