how do these compare?

[user]

hello

can you tell me please how do these compare:

1)
- a 6MP out-of-the-camera photo from a 6MP 1/1.7" camera
- a 6MP out-of-the-camera photo from a 12MP 1/1.7" camera (we make the 12MP camera to shoot at 6MP)

without any software post-processing and at the same ISO

2)
- a 6MP out-of-the-camera photo from a 6MP 1/1.7" camera
- a 6MP photo from a 12MP 1/1.7" camera, that is the result of a 12MP image converted to 6MP using software post-processing

at the same ISO

3)
how do each of the above comparisons may alter as ISO increases?

thanks

PS:
I mean how are the above comparisons expected to be according to the laws of physics, logic etc

then if someone has tested these, tell me the real life results

thanks