[Freesurfer] f.nii & f.nii.gz compatibility

Hi,

I am going to be running some new analyses on an old data set from another lab group that was collected in 2005/2006. Their group unpacked and analyzed using the f.nii.gz format; however, our lab unpacks and anayzes the f.nii format. Since I will be comparing the group from their lab with the group from our lab, do I need to re- unpack into f.nii or convert the already existing f.nii.gz files into f.nii ones, or are the two versions essentially the same and can be compared directly? What about if we want to combine some of their subjects with our subjects for a group analysis? Any advice would be greatly appreciated.

Thanks!

-Garth