So.. What is better for making routes? Can anyone breakdown the differences between Trainz 2010 and Railworks? Also, What's happened to the download station and I hear something about 2006 version is not supported?

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Ok, but this topic will end up being flamed heavily - there are a lot of users on these forums that cannot bear to hear anything but 'trainz is perfect'.
Route Creation:
Trainz is the better of the two here - barely. While railworks has built-in DEM support and splines work more reliably in it, it has some serious issues with stability - trackwork wil often 'vanish' myseriously when you save, leaving you with invisible track that should be visible, and the only option is to delete it. Junctions in railworks are prettier, but far more difficult to form - there are very limited angles where you can approach the track and it form a junction, also your mouse clicks have to be very precise for it to determine that you want a junction rather than crossing track.
Edit:
I meant to write more here about why I say 'barely'... Trainz' route creation is on the whole easier than Railworks, however, there are some lingering annoyances, such as trying to delete trackwork can often result in the wrong piece of track being deleted, and there are occasions where 'undo' doesn't exactly work. There are occasions where adding a piece of track results in it actually placing the track running off to infinity, and in a way that cannot be selected or deleted.
Also, working to realism and DEMs/Overlays involves buying TransDEM, which for someone that has no income like myself is actually horribly expensive - it costs as much as SnC did. There's also no way to try it to see if it actually does anything that you will benefit from. Roland of course has a right to ask money for it, it's his choice, but it does mean that Railworks with its built-in DEM support has an advantage there.
End Edit
Graphical Quality:
Here's a little less easy to say. Theoretically, trainz has the upper hand, as railworks has real problems with any textures above 1024x1024, and will very rapidly crash if you have too many large textures (as ikesmith's WD 2-8-0 and ROD 2-8-0 models proved). However, there is something more gritty and realistic about Railworks' visuals. It's very likely that it's an issue of the shaders, Railworks uses Direct3D shaders quite extensively, and the metal shaders provide a fairly realistic metal look, Trainz on the other hand is still mostly based on a 10+ year old OpenGL rendering model that lacks the realism of modern shaders.
Off-track scenery however is flat and uninspiring in Railworks, trees are billboarded, and don't look anywhere near as realistic as well-configured Speedtrees. When moving billboarded trees look bad, very bad.
The two are kind of diametric opposites in a sense, since trainz does a good job of looking good from a distance but looks plastic-y when you get close the action, whereas Railworks looks good close-up, but starts to look terrible as you zoom out for a wider look (this is somewhat route dependant, Newcastle-York Modern looks pretty fantastic zoomed out).
Quantity of Assets:
No competition here, Trainz has thousands more. Railworks has a very limited set of freeware assets, especially for rolling stock, but also scenery objects pale in comparison to Trainz. Rolling-stock wise, you WILL be paying, and expect to pay into the several hundred pound area to have enough of an assortment to model any specific region/era.
While TS2010 lacks freeware UK steam assets badly, you can at least buy a handful with the SnC pack, which is very reasonably priced compared to it's Railworks counterpart (WCML North offers less route, and only 1 new locomotive for a higher price than SnC 2009).
Driving Experience:
Railworks wins here, sadly. Consistant cabs and quantity of camera positions without hacks makes RW far more enjoyable while driving. Driving in trainz always involves setting some junctions by hand, no matter how hard you try. There is simply no equivalent to the ability to enter a timetable by stations and have the computer control the switching, unless you want to simply watch trainz' AI drive, which isn't really driving now is it?.
By default Railworks has AWS and other features enabled, whereas trainz will require third party rules added to a session to achieve anything similar, along with knowledge of the railway rules relevant to AWS, speed limits and signalling. Railworks 'just works' in this sense.
That said, Railworks' session creation can be frustrating, the AI is far dumber than trainz' AI, and creating drivable sessions with any AI presence requires experience and some trial-and-error. Often you can't even achieve what you really want, and have to compromise to get the AI to let you fit around it. Once you understand the railway operating procedures, and have mapped out the junctions and paths, trainz can provide far more rewarding sessions.
The quality of cab views in trainz is generally rubbish in comparision to Railworks, this is true of default AND third party locomotives. Although some freeware Railworks locomotives lack cabs, there are also many trainz locomotives that lack cabs. Sadly, since trainz lacks the quantity of camera views, a missing cab in trains is far more painful, as you cannot fall back on 'external looking-out-of-the-cab-window' mode that railworks provides even if a cab isn't available. Cabs *can* be made to look good in trainz, the steam engines in SnC prove that, but it seems to be something that many content creators don't care at all about.
A comparision of the default class 37 cabs on railworks and trainz shows just how bad the two compare, and bear in mind that RSC even went and released an updated class 37 later, which has a better cab still.
Railworks:
Trainz 2010:
Physics:
Railworks claims to have a better physics engine, and on the surface of things it may appear so. However, railwork's physics engine is hampered by long-standing (since RailSimulator) bugs that will likely never be fixed since RSC isn't interested in fixing things that aren't direct revenue sources.
Trainz' might not have the collisions of Railworks, but at least wagons don't jump in the air when you nudge into them at 1mph. There are notorious bugs in Railworks that result in such wonderful features as trains that accelerate by 20mph instantly when you release the brakes (even with 0% throttle), trains that can accelerate uphill with 1% throttle, and carriages/wagons that move by themselves.
Future Abilities:
Trainz wins here. There are only a few of the trainz flaws that cannot be overcome easily - noticably camera views and the ability for the simulator to handle switching for the driver, both of these need Auran's attention - all the rest can be improved by the userbase. Railworks isn't nearly as user-extendable, and since RSC are unable/unwilling to fix many issues, many problems with Railworks will remain there til the end of time.
Do not be fooled by the release on friday of 'Railworks 2' by the way, it is merely the same Railworks with a new 'casual player friendly' user interface for the cab controls. Functionality has not improved at all, and it is in no sense a 'new game'. The 'footy fans' over at UKTS love to point out that 'other companies do that, EA's NHL hasn't changed since 1998', but this ignores that those companies DO change their products for new releases. While hockey the sport hasn't changed since 1998, EA's hockey game has, significantly. Railworks has not.
Overall:
I'm not sure there's an overall winner, they're both good at some things, lousy at others, Trainz most certainly is more flexible and CAN be made to be better overall than Railworks (with minimal time investment by Auran, but a lot more by content creators). If you do opt for Railworks, make sure your credit card can handle it, you WILL need to buy a lot of 3rd party addons, regardless of how much you tell yourself 'I don't have to own every addon'.