Comparing the Texas Instruments SRAM IC chip BQ2201SN and BQ2201SN-N, what difference does the -N make?
The -N, which is the last digit of the part number, is for the Temperature range.
blank = Commercial (0 to +70°C)
N = Industrial (-40 to +85°C)
Click here for the datasheet, and this information is on page 11.