Rose 31 smells like pepper with a touch of rose, and Vetiver 46 is incense with vetiver underneath. I don't find them too much alike at all other than having 'sharp' dominant notes. The commonality is that the Le Labos don't necessarily smell like the note they are named after, especially not Patchouli 24. Aldehyde 44 is only mildly aldehydic. Gaiac 10 is amazing, but I don't know how much of a true gaiac note it contains (I've never smelled pure gaiac), but I don't think it's a lot.
Iris, Labdanum, and Vanille do smell like their names... the others I haven't tried, but that LS sample pack is on the way. Among the many I've tried none of them smell particularly alike.