Well, there are is an alphabet soup of Volatility spreads that a trader can enter in to. However , this is something which I came across recently and I believe is probably the best way to classify time spreads Vs Others.

Time spreads want low real volatility of the prices and high implied volatility. Trader does not want underlying to move but at the same time wants market expectation about the movement of underlying to strengthen. Under these seemingly opposing circumstances, a long time spread trader makes money. This is a great way to differentiate between all the rest of spreads like callback , putback,ratio vertical callback, ratio vertical put back ,straddle, strangle, butterflies etc, etc…The rest of the spreads depend upon similar movement of real vol and implied vol. BUT NOT time spreads!!

I am thankful to george who brought this difference out in a completely different context!