OK, that title seems to be stating the obvious, but a lot of people seem to expect Linux to be so much like Windows as to make no difference. But of course, Linux is quite different. For one thing, it's free open source software, so you don't have to pay for it. For another, it was not developed by a for-profit corporation that provides paid technical support.
Recently someone in the Go Firefox! forum on Delphi linked to Linux Is NOT Windows, written in 2006. Since then Linux has gotten easier to use for people who aren't all that geeky.
I'm a little bit geeky in that I did take a couple of courses at Boston University ten years ago for building computers and Windows NT. As part of that, I ended up learning quite a bit and did installations from DOS up through Windows XP. I can often figure out things, or at least find web sites that will explain stuff when I run into problems.
But there are limits to my geekiness, so when I decided to try Linux again I looked for something that would pretty much work right out of the box. Of course, there was no box, so I did have to know how to download an .iso file and burn it to a disk so it would boot, and I had to do that using Windows.
The article does a very good job of explaining the differences between Windows and Linux without getting overly technical. So many people have grown up with Windows that they may expect Linux to be very Windows-like without appreciating why is isn't and why the differences are good things. The article explains, again without getting overly technical, how Linux started and how and why it was developed and why the open source way of doing things is better once you accept certain things.
Realizing that open source software like Linux and the many applications that run on it are developed by volunteers who don't owe users anything is pretty important. If you have a problem, you can ask for help, but you have to realize people aren't being paid to help you, so it's best not to expect or demand instant gratification. I didn't have any problem with that in part because I'm used to the helpful information sharing I find on Delphi Forums and other places. Delphi's Go Firefox! forum is a place where people can ask for help with problems and people volunteer their knowledge to help solve them, but nobody's getting paid to do that.
I have to disagree with some points made in the last couple of paragraphs of Linux Is NOT Windows, and that probably has a lot to do with improvements in Linux over the past three years aimed at newer users. The author suggests if you want an operating system that does just about all of the heavly lifting for you, stick with Windows and make sure you've got a good firewall and good security software in place, or get a Mac and use OS X. Now three years later I'd be willing to bet that many people who might not have been good Linux candidates then would do very well with Linux Mint. At least, it was my choice. There are other versions out there that other people may find more to their liking, especially if they like playing around with geeky stuff more.
Linux Mint 7, aka Gloria, is the most up to date official release as I write this, and Mint 8, aka Helena, should be released very soon. I found that right off the CD Mint worked just fine for me. One thing I had to do was install a Dreamweaver substitute, Quanta Plus, so I could make some changes to my home page, a graphical web page of linked icons that resides on my computer, not on the web. I had to learn a few things to do that, but to me they didn't seem too terribly geeky. Anyone willing to search and follow instructions could do it.