Comparing the Westside M-4 to the Tenshodo M-4.
The Westside has an elesco feed water heater in front of the smoke stack.
The Tenshodo has more fine detail than the westside, ie, door outlines in front of cab, boiler jacket stays, extra piping and see through running boards.
The tenshodo tender has marker lights and see through castings on the truck wheel side frames.
The tenshodo also cost about twice as much as the westside (at least on what I paid for them) so you have to weigh the cost of what you're comfortable with versus detail. The tenshodo is also already painted.
The westside gives a very nice running engine with nice detail plus a nice caboose thrown in for a reasonable price.
Sam