Although the labels 'designer' and 'niche' are useful in the context of some discussions to infer the manufacturer's intent in creating the fragrance, where the fragrance is purchased, how it is marketed, etc. there are so many exceptions and a such a large gray area regarding what is 'niche' and what is 'designer' that the distinction simply isn't meaningful. The distinction is especially not meaningful in trying to cross-classify specific perfumes, as in "this designer smells like niche". What one is likely really asking is "what inexpensive and/or mass produced perfumes smell like expensive, limited distribution perfumes?"
The labels 'niche' and 'designer' are riddled with problems. For example Comme des Garcons is a designer fashion house, no different then Chanel or YSL, but CdG fragrances are thought of as 'niche' for a variety of reasons. Houses like Guerlain and Caron eschew both labels as they have perfumes distributed through designer channels (i.e. Shalimar) and other perfumes that are distributed like niche perfumes (i.e. L'Art et la Matiere line). There are then 'designer' houses that have niche lines (i.e. Hermessence, Chanel Exclusifs) and niche houses with mass-produced lines (i.e. ELdOs Editions des Sens line). Even houses that are thought of as niche, let's say Creed, are distributed like designer perfumes through every e-tailer and even outlets like Costco.com.
What is valuable about a discussion like this is the realization that good and bad perfumes can come from anywhere. For example I find L'Instant de Guerlain on par quality-wise and construction-wise with any "niche" perfume. Conversely the Boadicea the Victorious and Brecourt "niche" lines are no better then anything you'd find at a mall perfumania. Of course if you go back a generation, before the advent of the 'niche' perfume concept, one sees that the perfumes of the designer houses like Chanel, Dior, Lanvin, etc. were the 'niche perfumes' of their day, created by the world's best noses and employing the best materials while the drug-store perfumes were the common perfumes of their day.