Here’s the skinny on the exploding world of blogs: First, the word ‘blog’ is a confluence of two words – ‘web’ and ‘log,’ as in, a ‘log’ or journal that sits on the web. Think “Captain’s Log, Star Date 50 jillion.”
Here’s the image you should keep in mind: I went to London once when I was a kid, and I was stunned to come upon a bunch of people standing on milk crates, all over a public park, talking loudly. Some of the people shouting their opinions from the top of their crates were surrounded by huge crowds. Others were surrounded by pigeons. The quality of the talk varied widely. Either way, everybody had something to say.
That’s a blog, only, your milk crate is online. It’s a personal space created by someone to voice his or her opinions or update people on his or her goings-on. Like a web site, it can be found by people using a browser, it uses regular URL addresses, and it may have advertising attached to it.
So to answer your question, a blog really is a website, but it’s often updated more often (something the search engines of the world notice, meaning you can get on their radar faster) and is designed to make it easy for people to post their comments, videos, pictures, and so on.
Finally, a blog is better designed than a web site for two-way communication, meaning visitors can easily leave feedback in the form of notes, pictures or video. If you want to set a blog up yourself and talk to the world (or the pigeons) about whatever you want, you can do it in minutes, for free. One easy site is at blogspot.com, but I’d welcome any other suggestions.