I suppose there are two major differences, one is that Sarcococca is much hardier than the Osmanthus and the second is that the Sarcococca (here anyway) reserves all it's flowers for those dark days after Christmas and thru the worst of our weather.
In Ireland, Osmanthus fragrans is grown in shelter or even on walls for protection, whereas the Sarcococca will slum it anywhere. I am not sure which scent wins out, I suppose that aspect is personal but the Sarcococca wins hands down for me.
So, is it the sweet olive that you have growing well in South Carolina, or the sweet box (sarcococcus?) So often the zone information we are given will let us know if it gets too cold for a plant in our zone, but it doesn't tell us if the plant will thrive in the heat. So, if sarcoccus does well in South Carolina, I'm guessing it would thrive in Central Virginia, too?
Good Point, Wendy. In Ireland we have either the best of both worlds or the worst of both worlds, depending on your point of view. Our martime climate is cool and wet in summer and cooller and wetter in winter. Zones don't tell you about things like 'winter wet' and plant that refuse to hibernate.