Hi locherbread
The texture pack that you downloaded (the new TS2009 ground textures) will not simply update the graphics, and don't replace any existing textures. They are ground textures made to the new 09 methods for people to use on their layouts.
As to the high res content shown in the screenshots on the website. These are included in the program, but are not used on any built-in layouts/sessions. They are as follows (names may not be 100% correct):
Station Wallangarra (scenery)
UP SD40-2 (train)
TS2009 track (track)
Tree (scenery)
Road 2l hwy (spline)
car 51-54 (scenery)
hedge (spline)
stones with puddles (ground texture)
These items are included as examples of the newer methods of content creation. As is on the TS2009 website, TS2009 when first released was mainly intended for creators (either assets or layouts, any other 'creation' that can be used in game), and included only a limited amount of new content in it. However, it introduced a number of new features, that either creators or route builders can make use of, such as the 5m grid. Effectively it still is intended for creators, however the expanding range of assets for it means that the end user also can make use of it even more.
Of course, to use the new 09 assets on the download station, you will need to have TS2009.