Difference between SLR/c and SLR/n?

So, which are main differences, besides those obvious?

Obvious are that Canon is based on Sigma body, Nikon on F80. How much they share inside? Except sensor which I suspect is same. Similar shutter? (hopefully)

For example I know there are special firmwares after official ones for SLR/n, are there any for SLR/c or they were not needed?

Is one of them more prone to fail then other? Any other known problems of just one them? I know most faults of SLR/n, but pretty much know near zero about SLR/c.

Thanks for answers, if there will be any.