like what is difference between nfet 03v3 and nfet 05,so basically it is difference in operating voltage only right due to change in minimum gate length requirement

There is no such thing as an "nfet 03v3" in the SkyWater process. There are 1.8V (thin oxide) and 5.0V (thick oxide). If you are running at 3.3V power supply, then you want the 5.0V devices (e.g.,

nfet_g5v0d10v5

and

pfet_g5v0d10v5

).