Hi,(Newbie) This Christmas I received a Lionel O-27 gauge Santa Fe Hudson setup from my wife. I also received an MTH "O" gauge caboose(Central Jersey Line) from my brother. The MTH caboose seems to be of a larger scale than the one that comes with the Lionel setup. Is there actually a size variance between the two "O's?" If so, how can I tell the difference when I go to purchase additional rolling stock? (I do not see any differential markings on the Lionel boxes) On another note, I have been currently limited to a 4'x8' setup. If anyone knows of some interesting layouts limited to 4x8, let me know. Thanks!