The only "compatability" comes if you have built 3D models in an application which exports to all three sims (MSTS, TRS and RS/RW) if you have the source files then you can use the models in more than one sim. However even then in the case of more complex models, e.g. with moving parts the conventions for attaching etc. parts and components is quite different.
If you've used Google Earth to create a kml file of markers for an MSTS route then these could be imported via Transdem into TRS (or used for RS/RW) but there are better and quicker ways of getting geographic information into TRS.
However you can't take a finished route or item of rolling stock in any of the three big sims and use it in one of the others.