While you say you know what an Operating System (OS) is, I'm not convinced you understand the concept of a distribution (distro).

In basic terms from a Linux perspective (ignoring the technicalities of GNU + Linux kernel and/or each BSD has its own kernel and/or Android's java vm within a Linux scratchbox scenario) you have a collection of software maintained generally by more or less a certain group of people with certain architecture in mind typically and while any distro "can" technically be turned into another distro (this is rarely the case, tends to brick installs)...

Ok I lost you, showing not telling is key for this - particularly people who are used to the tunnel vision of Windows or OSX for that matter.

The entire [software] project around which the Nokia 770, N800, and N810 has been created is referred to as Maemo. The default OS on the tablet is Linux. The default distro on the Nokia N810 is "OS 2008". The default release is codenamed "Chinook". You are going to want to upgrade to the "Diablo" and the most recent kernel (and other stuff that comes with these "Software Security Updates"/SSU). This is designed with a touch screen in mind as well as the rest of the hardware associated with the "Internet Tablet"/tiny computer. There are quite a few repositories (you can kind of think of these as FTP servers containing program installers all in one place; note I am dumbing this down for people that haven't used Linux before - devs please along, no need to critique this post) and has "hildonized" applications, which ranges from applications ported to the platform that play nice with the window manager all the way to games like Bomberman with big finger-friendly buttons. It's a nice environment and you'll want to stay. But there are limitations...

Ok moving on...Debian...oh Debian...Debian is one of the main foundation Linux distros, known for its stability. Ubuntu, Knoppix and others have been derived from Debian (and continue to suck at its teet - can I say that?). Once upon a time "Maemo" more like OS 2006 was [loosely] derived from Debian. Or so they say. It has evolved into a beast of its own that's for sure. Now there are several proper Debian ports for the tablets, with .deb repos filled with the proper ARM packages - of course several of those projects are long-dead. There is always the option of "EasyDeb Turbo-charged" a virtual install that can be accessed if you want to get your Deb on real quick. You get Java support, Firefox (excuse me Iceweasel due to Debian's squabble with Mozilla) and OpenOffice. You also can move windows around - yes "Maemo" has multitasking support but each window is treated like it's in its own private virtual desktop. With Debian and even EasyDeb windows can be moved around and you can have multiple windows on screen simultaneously. Deblet might be worth it if you want to play around with keymaps and other usability configurations.

Codename Fremantle is the next release from Nokia for project Maemo. It's designed for OMAP3 hardware a.k.a. the successor to the N810 and can't be run on the N810 due to the difference in architecture. Mer is a project starting by the community to implement all the features from Fremantle (or most of them anyway) into our own "distro"/release for N800/N810 (perhaps 770 owners too? Haven't looked into that, maybe they'll get Mer Hacker Edition). Mer is a work in progress and its going to be awhile before everything gets ported.

Android as I'm sure you've heard is Google's foreway into a mobile OS. It is basically a custom Java virtual machine running in a Linux "scratchbox" - that is it runs on top of Linux. Applications are "Java"-based and thus should be architecture independent. There is a release for pre-1.0 Android virtual install for the N810 that has been completely unusable for me. There is also project NITdroid which is full Android (1.0 not 1.5/"cupcake") with work-in-progress custom drivers to get the touchscreen to work, keyboard to work, reverse-engineered wifi driver, etc. No gps, no bt, no audio atm. Oh and something that no one ever seems to point out.....gonna go bold for this nugget.

Kernels must be flashed to the device, there is no true multi-boot action going on. There is no Grub boot loader that loads the kernel of your choice. The kernel is flashed on the device as if it were a digital camera and not a friggen portable computer.

Yes there is dual-boot support. You can have Chinook on a SD card and Diablo on the internal flash memory but you can't have Android on an SD card. No. You can chainload some distros perhaps, rig that to work, but for the time being Android and other radically different OSes, no - have to flash the device. And in doing so (unlike flashing to get screen rotate working) Diablo/Chinook won't boot. Have to re-flash to get them to boot again. Frustrating is what it is. There are all kind of little frustrations associated with the device but there are more positives to it than negatives at least for me.

Garnet VM is a Palm emulator, it runs within "Maemo" much like the Gameboy emulator does. It can't run every Palm app because of hardware limitations but it can run quite a few and perhaps not use all functions but hey it's something.

VMware - vmware is not currently available on the device (though virtual machines of the device are). And no technically this isn't true. VMware quite awhile ago showed off a demo of Windows CE and Android running side by side on the device booted from some custom VMware environment - and no we can't get our hands on it, cause VMware is holding out on us. Teasing us.

I guess there is yet another group of things, applications with plugins, full-screen, virtual Window Manager types - Canola, Carman, Mediabox, etc. Which act kinda of like XBMC, essentially overlayed KIOSK-esque environments to do things such as play media.

I'd also like that I've never understood the fascination behind screenshots and videos comparing Linux releases - the real differences are behind the scenes, the only features shown in a screenshot are the wallpaper, window manager and theme. Hands-on (plus perhaps a feature list or changelog) really has no substitute here.

If someone would like expand on the above rather than redirect to a broken page or unrelated thread please do so.