Not sure, but except in the case of a blizzard, snow conditions are generally SMOOTHER. Snow requires low pressure and a dew point just around 32ish degrees, if it is precipitating out of the sky, the winds are not whipping it back up into the clouds so they are somewhat calmer. However, snow is never very high in the atmosphere, you will only ever fly though it on approach or take off, not at cruise.
Based on my very limited knowledge of turbulence, most turbulence is caused by wind. Therefore, you can fly through rain and have no bumps whatsoever, but you can fly through rain and have a really bumpy ride. The same would apply to snow. It all depends on the wind.