The graphics are very similar and seem to use a few of the same environment models, but there are some differences, like Zap's walking animation in TT (It's basically the same but his left from paw is turned inward) and the lighting is not as good as SF.
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Hey is there anything you want me to bring for the rest of the week and if so it’s so cool that you can do something and just do it like that
Models don't depend on the graphics engine. But dunno why the changes in lightning when graphics are the same, someone more familiar with game engines might be able to explain it.
--- Power is the thesis (power, power) Crimson on my lips, when I smile I'm a t-rex
They both use the same engine VV purchased in early 1990 (Alchemy), but both developers have their own codebase. It would be interesting to know how they share the IP between developers.