Tamiya Part # 53841
http://www.tamiyausa.com/product/ite...oduct-id=53841
The differences are very subtle between the 2 options...
The front one way acts like a spool when on power, whereas the centre one way/front diff combination does not. The spool action when on power of the front one way can really help to pull your car out of the corners (essentially allowing you to blam on the throttle harder and sooner).
When off power or braking, both the centre one way and the front one way work exactly the same. That is, the front wheels are free to rotate. In an extreme example, when hard braking and the rear wheels lock up the front wheels wont when using either the centre or front one ways.
The front one way does not provide any diff action across the front wheels, but I guess could be considered to be like a really really loose diff when off power. Like in a diff, each of the front wheels can rotate at different speeds.
When using a centre one way and front diff combination, the front wheels are free to continue rotating unretarded by the rear. In this way, the front one way and centre one way act the same.
However, using the centre one way with a front diff gives you a level of adjustability over how loose or tight the diff action on the front wheels are. A front one way only has a really loose diff setting, wherease the front diff can be adjusted from loose to tight. You can use the diff to tune the handling charactistics of your car through the corners.
I guess to summarise..
Front one way allows aggressive turn in on the corners and pulls out hard due to its spool like action when on power.
Centre one way + front diff allows aggressive turn in but offers adjustability of the diff action.
Neither options allow 4 wheel braking, only the rears will slow the car down. This can be seen to be bad as if you brake whilst turning the car will have a tendancy to lose traction and swing out in the rear (overcome this by braking in straight lines only).
Others might have differing opinions or might be able to suggest some more differences between the two
-Mark