You ask a difficult question. As tobacco color-cures and subsequently ages (and is kilned or fermented), scores of volatile compounds are created. These are relatively light weight compounds (less that about 300 grams per mole), and can be detected by the nose. These are often esters, terpenes, amines, alcohols, aldehydes, esters, ketones, lactones, thiols etc. While a single compound may present the aroma of a specifically identifiable scent (e.g. diacetyl-->butter), the same "scent" may also be triggered by other compounds. At least two distinct compounds are recognized as "anise" aroma. Several different aldehydes say "chocolate" to the nose.
Another phenomenon is that certain combinations of aroma compounds together may trigger identifiable scents. Most recognizable fruit aromas result from a combination of aroma compounds. (This is why we may say, "fruity," when we can't pinpoint the particular fruit.)
So, setting aside the possibility of adding specific flavorants to tobacco, which is seldom done with cigars, just the natural chemical interactions within the cured, aging leaf can generate a host of aroma compounds, depending on the conditions of temperature, humidity, ambient pH and the abundance or scarcity of oxygen. If any research has explored the specific aroma compounds of cigar leaf (which could be done with various chromatography and spectrometry techniques, analyzing "head space" air within a container of tobacco), I'm not aware of it. [It has been done and published for Cyprus Latakia.] My guess is that it would be different for nearly every variety of tobacco, as well as every stalk level, every plantation and every crop year.
And I've left out a discussion of the additional aroma compounds produced by combustion (at various temperatures and humidity).
Bob