general musings....

Looking at the stuff available on ebay... there is a huge amount of different sets and bits out there. The older Tomy sets with the dark blue rails are 'mostly' compatible with the newer stuff with the light blue rails. The main difference being that with the earlier sets, the locomotives are bigger than the present ones and may not fit under the bridges of the new sets. These older locos also are able to be reversed by the special reversing track, which flicks a switch under the loco body between the wheels. These special switches are often built-in to some of the things like the 'Engine shed' with the workmen hanging upside-down from the roof, and the train wash and lumber tipper. Of course, they have no effect on the new locos which do not have the reversing capabilities. Another thing I noticed about the older sets is that the long sloping rails to take a train up and down from the high track have 'teeth' along the sides which engage in similar teeth on the outside of the loco driving wheels, obviously to help the train ascend the incline without slipping back. The new locos do not have these teeth on their wheels so if used with these steeper inclines may come into difficulties. The red high track supports of the older sets are quite a bit higher than the newer series, and are needed to go with the dark blue sloping rails. They can be combined with newer stuff, just be aware of the differences when planning your layout. I find that, because I tend to make my layouts as a long continuous track, I have the trains ascending the newer style slopes and rising curves to get to either a 'double-height' or 'one and a half' height which is similar to the red supports, and then descending by the steeper dark blue sloping rails.
The older Tomy sets came out before the Thomas & Friends craze took-off, so the engines and trucks are more 'toy' like. They and the stations and other accessories do have 'Lego' type studs though, so they can be built upon and added to with the huge range of Lego bits and blocks. For example the truck bodies often remove from their chassis, leaving a row of lego studs which could be added to.
There is a large four legged Crane which has little wheels built into the base for moving around, and can lift logs with a special hand. No longer part of the Tomy range, this goes well with the Timber yard set which dumps logs into a special tipping wagon which then tips them into a hopper beside the track.