I'm a noob to TSW and have just started with TSW3 on PS4. I have the standard 3 routes with the main game. Just wondering what to expect if I buy TSW2 add on routes? Will I notice any lower quality using older routes in terms of the graphics and do these older routes also come with new scenarios and timetables?
The tsw3 base routes (cp, sehs, skw, sos) have the new lighting and volumetric clouds, effects. All tsw3 routes going forward will also have that feature. All the other routes have just dynamic weather, sparks and such, so no new lighting or clouds. Dynamic weather seems to impact performance a lot in some routes. And on the base routes, lowering the sky quality gives you plenty of fps. Some routes will have lower quality cuz well they are a few years old. Scenarios haven't changed and timetables are mostly the same. Some routes got new timetables such as rapid transit, hbl, ska from the new journeys expansion. And all got the preservation update that brought them up to tsw2 standard
It seems to vary a lot on PC, I expect the same for consoles. Some look and drive great, lights work and trains behave as expected. Other routes don't have working lights, or they look weird, or the trains have bugs or wrong behaviour.
Every single route addon comes with a timetable, at least one locomotive with a tutorial, a handful of scenarios and collectibles. Most locos are compatible with Livery Designer, although a few may still not be. Some DLC "talk" to each other to add trains and services to each other. However on PS4 a handful of those extra services are not available, for performance reasons. If at some point you decide to upgrade to a PS5, the game and DLC upgrade to PS5 for free, and you can access those few missing services as well as better frame rate, resolution, and textures. Every single DLC release has been showcased on the official Train Sim World YouTube channel close to their launch. Even when they add some new features to old routes, they look and play fundamentally the same as on launch day. If you just watch the first ~20 minutes of those streams, It can give you a better idea of what is included with each add-on. You can also check the reviews on Steam because they are usually the most thought out feedback from the community, and PlayStation doesn't have user reviews for anything. They are virtually the same except for the aforementioned missing services, and better performance depending on the PC hardware.
In regards to German DLCs and info about which trains are being shared between the routes you may find this file created by breblimator very useful: https://docs.google.com/spreadsheets/d/1W5-ueaP4-UmdhZMKpdH0yTADmY4gNyMw_dRNi86G57o/edit#gid=0 It's not up-to-date but still can give you an idea to plan which DLCs to buy if you want a particular German route to be more busy.
No SKA New Journeys new timetable data No AI scenery trains data (some routes) No HBK enhancements to the timetable data