I have figured it out !
sub! issue was solved when I removed PDIFCT contacts from GND. I didn't have to create a label for sub!; Calibre LVS was able to identify the global sub! net without label.
ME are the transistors (both epm & enm) from source/schematic.
MP are the transistors (pepm) from layout
MN are the transistors (nepm) from layout
Although my schematic and layout was build in similar technology file (PDK); while creating netlist for schematic- device was recognize as ME and while creating gds from Layout- device was recognize as MP and MN ! So, i modified the netlist devices to match with layout i.e. changed epm to pepm and enm to nenm.
Lastly, in netlist, the device property (l/w) unit was in meter range. I have changed the unit to micron and issue with "Device Property Error" was taken care of. Now, the LVS is clean.
Thanks
--Swapan