Using ESRI arcpy GetParameter, instead of python sys.argv

There are two options for passing parameters to your python script in ArcMap.
1) Using the python sys library.
2) Using ESRI arcpy library.
grasslandSelect = sys.argv[1]
grasslandSelect = arcpy.GetParameter(0)

There are some obvious differences. Python uses the argv[0] to pass the argument of the actual python script, so the first argument entered in the command line is argv[1].
ESRI GetParameter(0) is the first parameter passed when calling the script from a Toolbox.

For the case of Boolean arguments, it is worth mentioning that sys.argv will return ,with a lower case, 'true' or 'false' while arcpy.GetParameter will return, with a capital, 'True' or 'False'. Though I had not problems complementing either(not True, not true), I did have some unidentified issues using the lower case 'true/false'