The difference to the user is in terms of configurability
With linux you always have a choice. There's different ways to achieve a great many things, but you need some technical know-how to do it. If you have that know-how you'll be a lot more productive when using Linux than Windows. Configuring it all from the ground up will be a pain but you know exactly what's in your operating system.
With windows, not so much. You don't need so much knowledge, it works pretty much out of the box, everything is tested for compatibility, etc. development of third party applications is still fairly open, though.
With mac, even development is shut up tight. The network protocols are forgeted up simply so if you want to use macs in an office network, you're probably going to need mac servers as well (there's another $8,000 down the drain). You do get the advantage of a unix shell though, so stuff you can do in a linux terminal, a lot of it can be done the same way on a mac.
Ultimately, it comes down to one thing: What you need to do. If you need the extra configurability but need it to 'just work', go for windows. If you just need a functioning OS and an empty wallet, go mac! If you need it to be cheap and configurable and you really want to go through with it, grab a linux distro. There is no 'right' choice. It's all down to the user.
