I checked out the two tenders. The one that comes with the turbine has a plastic shell, 4 wheel diecast trucks, lettered for Lionel Lines. The prime mover sounds are the same. Whistle, bell, and crewtalk are different. The base is diecast to give it some weight.
The add on tender is lettered for Pennsylvania. It has a die cast body and frame. It also has back up lights and a water scoop underneath. It also has 6 wheel diecast trucks. The whistle is more throaty.