everyone needs to own or have downloaded the same plane. Say for example you have the C310 but nobody else does, they will see the model for the closest matching plane. Sometimes not (like a330 for a cessna for ex) but that’s a sim issue you can’t do much about.
In the settings, under “Traffic” make sure “Use generic model” is turned Off for both Multiplayer and AI Traffic
The exact plane AND livery must be downloaded by all users