Basic View NX2 question... what does it do?

I use View NX2 to convert NEF files, but I'm a bit unclear what it is doing.

My undestanding was that NEF/RAW files are converted without change and then need to be edited in PS, Apertue etc? If so, why does an NX2>TIFF>PS converted file look different than an ACR>PS file? Obviously, the NX2 conversion is making changes to the NEF file. But the question is, what is it doing?

Is NX2 applying the camera settings to files during conversion, or is applying NX2 software settings settings?

If I go into "Edit" in NX2 and make changes, are those changes applied in addition to the camera settings, in place of the camera settings or neither?

Any input would be appreciated,

Brian