Possibly by different creators (although I'm pretty sure they are Rob's cars, I know the loco is!).
Or, different times when they were created. It's possible that the creator produced an updated set of carriages, or at least planned an upgraded set.
Both items date back to the UTC days, and as such placing them into current versions may cause issues with the models, including different lighting (particularly if one of the items had been updated for it's re-release - I believe Alex23 did do some upgrades for them to work with TRS2004+ when he released then under his username; with permission from Rob).
I would highly suggest you try to make your messages a little less short. I understand that English may not be your first language. However, your messages do come across as rude in some cases, or as attacks. This may not be intended, however it may mean that you are less likely to receive assistance.