Microvesicles form differently than exosomes: instead of being assembled inside an internal cell compartment, they bud outward directly from the plasma membrane and pinch off into the surrounding fluid. That different point of origin is the formal distinction between the two subtypes, though in practice the size ranges of microvesicles and exosomes overlap enough that size alone cannot reliably separate them.
Because confirming the actual budding pathway for a given particle population requires specialized study, a commercial particle preparation may not have been rigorously sorted into exosome versus microvesicle fractions. Consensus reporting guidance addresses this by recommending that suppliers describe what was actually measured, such as size, concentration and markers, and use the general term extracellular vesicle unless the specific biogenesis pathway has been demonstrated.
For a buyer comparing products, the presence of the word 'microvesicle' or 'exosome' on a label is less informative than the characterization data behind it. Request the isolation method, the analytical methods used, such as nanoparticle tracking analysis or marker assays, and the resulting measurements, and treat the subtype name as a label rather than a verified fact about the product. FDA states there are no FDA-approved exosome products; these preparations are generally regulated as biologic drugs under section 351 of the PHS Act, and purchase and clinical-use decisions belong to the physician and their own regulatory counsel.
Understanding that microvesicle and exosome labels describe formation pathways, not guaranteed facts about a given product, helps a buyer ask better questions of a supplier.