To clear up some of the confusion:
Neroli is the name given to the essential oil derived from the steam distillation of orange blossom flowers from the bitter orange tree (Citrus aurantium); orange blossom (or, more correctly, orange blossom absolute) is the name give to the absolute from produced by hydrocarbon solvent extraction from the same orange blossom flowers. They have different scent profiles; the absolute tends to be closer to nature since the solvent extraction process leaves most of the orange blossoms’ aromatic constituents untouched. This is not the case with steam distillation of the orange blossoms from which you get a different set of aromatic constituents and hence a different scent profile for the neroli essential oil that is the end product. This is mainly because steam distillation is actually a more invasive, destructive process than solvent extraction. With steam distillation a number of other chemical process are set in motion that destroy some aromatic compounds of the original orange blossoms; hence the difference between the orange blossom absolute and the neroli essential oil. Orange blossom absolute has a defining heavy indolic note; neroli essential oil tends to be more buoyant, fresh, bright, more woody florally than the absolute with a barely perceptible indolic presence and can be somewhat sharper than the more diffuse orange blossom absolute depending on the quality of the orange blossoms, the nature of the distillation process, and the expertise of the distiller.
The orange blossom notes one finds in today’s fragrances are aromachemical reconstitutions/interpretations of the orange blossom absolute that tend to deemphasize to a certain extent its indolic headiness. I tend to think of aromachemical orange blossom reconstitutions as sanitized orange blossom notes, because, more often than not, the characteristic fecal component of indole’s scent profile is down played. The characteristic diffusiveness of the absolute is still there, but the delightful orangey floral indolic fullness is somewhat attenuated as a result. To obtain this synthetic, less heady indolic orange blossom fragrance, compounds such as indole, pheny ethyl acetate, and aurantiol are reduced or removed. There are about a dozen of these different aroma chemical elements—mostly esters and alcohols—that can produce a wide spectrum of orange blossom absolute and also neroli effects depending on how they are modulated. Needless to say, that while these orange blossom absolute and neroli effects are somewhat congruent with the natural products which the seek to mimic, they do not entirely match the complex multivalent naturalness and complex floralcy of the orange blossom absolute and neroli essential oil. Think of them as two dimensional simulacra aromatics rather than the three dimensional nature specific aromatics they mimic.