While the provenance of vetiver oil certainly has a significant bearing on how vetiver smells, in practical terms in modern day perfumery, variations in the scent profile of vetiver have a lot more to do with how individual vetiver oil is processed--what constituents of the essential oil are left in, which ones are intensified/isolated, and also whether or not other aroma chemicals in the fragrance have vetiver-like notes that add to the complexity of the overall vetiver effect. This explains the large variations one finds among vetivers in fragrances more so than does the reality of provenance. Notice the way the use of vetiver is characterized in Frederic Malle's Editions de Parfums Vétiver Extraordinaire created by Dominique Ropion: "Dominique Ropion introduces a new essence of Vetiver, stripped of its bitter edge, which he matches with five woody notes to play up the scent's various facets."
Since it is costly to produce and isolate vetiver compounds synthetically from non-natural sources because of their complexity, most components of vetiver are isolated from the actual vetiver oil itself, and specifically from the isolation of vetiverol, which itself contains a number of other constituents that can further be refined and isolated to produce further "vetiver effects." Vetiver oil, like most essential oils today, is hardly ever used neat in modern day perfumery but, rather, becomes the starting point for other processes of refinement, extraction, and separation for production of odorant constituents, which are then used in specific fragrance applications. Since vetiver is relatively cheap to buy but costly to isolate from non-natural sources, the use of vetiver oil (mainly from Réunion, Java, and Haiti) as a starting point for the production of a host of "vetiver effects" is as much a case of economic necessity as it is a case of consistency and readiness of supply and, of course, a case of the ability to achieve specific, managed, and, most importantly, consistent effects that might not otherwise be achievable from the natural oil given the vagaries of supply (fluctuations in weather, market prices, politics etc.).
Vetiver in modern day fragrances is one of the most chemically manipulated notes in use today and has been so ever since the late 1950s when, shortly thereafter, Jean-Paul Guerlain, for example, used a more highly rectified vetiveryl acetate as the main vetiver constituent in Guerlain Vetiver. Vetiveryl acetate is derived from vetiver oil itself. According to chemist Bo Jensen "vetiveryl acetate, is created by acetylating the sesquiterpene alcohols presents in the oil. It has an elegant, soft, fruity-woody character", and not the smokey, burnt, rough and pungent initial quality that tends to generally dominate the unrefined oil before it begins to dry down.
The higher the vetiverol content of vetiver, the less smoky the vetiver will be. It also tends to be more rooty in nature than the vetiveryl acetate, so that more than likely, for example, MPG's Route de Vetiver probably contains significant quantities of vetiverol in proportion to vetiveryl acetate. Vetivone, another constituent of vetiver oil, is what gives some vetiver notes that rich deep woody peppery note.