Can anyone describe the difference between these two snuffs. S.M. Brown is said to be Menthol and Eucalyptus while S.M. 500 is said to be Chinese Menthol and Eucalyptus . Is there much of a difference if at all? I have S.M. Blue which is Menthol and Camphor and I can tell the difference between that and the Brown but what about the Brown and 500?