torquemad

Ec2: Your basic server. This would be your web server or VPS in traditional means, but it can be anything you want. There's an entire market place, where you can start pre-built Ec2 instances. You can also make your own, and create an "AMI" or Amazon Machine Image. This is your entire computer, configurations, installs, everything captured into a file, which can turn into as many computers as a you want, at any compute size/performance you want.
S3: Essentially a hard drive with a network interface attached to it. Think of it like a NAS drive. It can't do any language processing like PHP, but it can serve files without the need for a web server. Expands dynamically, so it doesn't have a contained size, it will also expand to meet traffic needs. Everything is stored redundantly, in multiple physical locations, although that is designed for resilience, not performance. It does not serve attached hard drive functions very well in the same way a NAS doesn't act like a native hard drive. Also, attach it to a Cloud

torquemad

// Use Gists to store code you would like to remember later on
console.log(window); // log the "window" object to the console