The constructional difference — how they are built
The achkan is the more tailored, more structured of the two long coats. It uses canvassing and chest interfacing similar to a Western coat, which gives it a defined silhouette that holds its shape from shoulder to hem. The sherwani is typically made with less internal structure and relies more on the body of the fabric — particularly in brocade or velvet — to maintain its form. The result is that the achkan reads as more architectural and precisely tailored; the sherwani reads as more fabric-rich and ornamental.
In terms of embellishment, the achkan is typically less embroidered than the sherwani. The achkan relies on the quality of its construction and the quality of its cloth to achieve its effect; embroidery, where present, is typically restrained — a border at the collar and cuffs, perhaps a small chest motif. The sherwani more often features all-over or heavy embroidery as the garment's primary visual statement.
Choosing between sherwani and achkan
Choose the sherwani when the occasion is maximally ceremonial and the visual richness of the garment is appropriate — the groom's outfit, the most formal religious occasion, a state event where Indian formal dress at its most elaborate is expected. The sherwani's embellishment and fabric richness signal that this is an occasion of the highest importance.
Choose the achkan when you want the formality of the long coat without the ornamentation of the sherwani — for a groom who prefers an understated aesthetic, for a non-groom family member who wants to dress very formally at a wedding without approaching the groom's level of decoration, or for any formal Indian occasion where the quality of the tailoring rather than the richness of the embroidery is the intended statement. The achkan in fine raw silk or a quality suiting wool, without embroidery, is a garment of quiet magnificence.