The Emissary-class had a short hull section, but rather wide and pointed saucer section. The class' pylons were angled downward and its nacelles had recessed Bussard collectors and a field grille that protruded in an oval-like pattern across the housing, making the back end of the nacelle look slightly disjointed.
Beginning in the early 2390s, the Starfleet Corps of Engineers advocated a plan that called for modular ship designs, where components could easily be switched out or replaced. Modular construction had been a part of Starfleet design philosophy for decades, but was greatly expanded after the Dominion War. As part of this new design system, when Starfleet engineers developed the Emissary-class they also designed the Nomad, Sentinel, and Vanguard variants.
The Nomad-class was more armored than the other variants and had a much wider saucer section with a slightly shorter hull section. The nacelle pylons were further forward and the starship shared a similar to the Luna-class and Envoy-class nacelle designs. In contrast to other variants, the ship's torpedo launchers were located to the side of the saucer and hull sections instead of pointing directly fore and aft.
Compared to the other Emissary variants, the Sentinel-class had a shorter saucer with stylings reminiscent of the Sovereign-class. The nacelles had a pointed edge on both ends, with the bussard collectors recessed to the side and pushed forward by the pylons. It had elevated fins that traced the hull and saucer section.
The Vanguard variant had a longer, more carved out saucer than other the other starships of the Emissary line. The hull was slightly longer than the other variants and had various armored sections. Its pylons were taller than the Sentinel-class and pushed aft instead of fore. The nacelles were only pointed at the aft end, with more traditional bussard collectors at the front.
USS Bonaventure (Emissary-class, NCC-102-A)
USS Crazy Horse (Nomad-class, NCC-50446-B)
USS Emissary (prototype, NCC-96003)
USS Laub (Nomad-class, NCC-95789)
USS McKinley (Vanguard-class)
USS Montgomery Scott (Sentinel-class, NCC-95792)
USS Navras (NCC-94010)
USS Nomad (prototype Nomad-class, NCC-53713)
USS Satie (NCC-96003)
USS Sentinel (prototype Sentinel-class)
USS Vanguard (prototype Vanguard-class, NCC-94996)