how is Linux different from Windows
How is Toyota different from Ford? No, I'm serious...Both are cars, run on the same gas and have 4 tires, but the resemblance ends there. Then again, depending on which desktop you use the Linux desktop itself can be much different or very similar, plus you can easily log out of one and into another if you want a change of pace.
Like in compatability
Hardware or between each other? Back to the Ford/Toyota analogy, abot the only thing interchangeable between the two is the tires and possibly the battery, depends on which models you're dealing with.
So...software inter-compatibility-none. A Wine emulator is available that is intended to let Linux run Windows software, I've never tried it and last I heard it was still unreliable at best.
Hardware compatibility- Good. I have a couple of older devices Linux won't recognize, Intel web cam and 3 or 4 scanners, scanner companies have been really stingy about providing open source developers with technical data so Linux drivers can be written for their hardware. Other than a couple of items here and there, I've found hardware compatibility to be good. Even my Lexar USB drive works with Mandrake 9.2 and 10.
Getting better all the time. Mandrake 8.1 was my first attempt at Linux, it worked well but gave me trouble trying to network it, 9.2 and 10 seem to be more user friendly, I haven't tried to network either.
Best thing to do is go grab a copy of Knoppix and check it out without fear of risking your OS, Feather Linux is a lot smaller and an easy overnight download if you're on slow dial up, same for Damn Small Linux. I've used both, they work great but have limited applications to keep the total size down. Both will fit on a business card CD. All 3, Knoppix, DSL and Feather have a tutorial file that opens on start up, you just put in the CD (while running Windows if you wish) and reboot, make sure BIOS is set to boot to CD first, and you'll boot right into Linux. Shut down, reboot and you're back in Windows, the hard drive is never touched. If you like it, then consider a full distribution. If you don't, you haven't changed a thing, Windows should still be installed and running with no changes made at all.