Enterprise-B navigates a solar flare

Excelsior orbits a planet

Enterprise-B heads towards the Nexis in ST: Generations

Enterprise-A and Excelsior depart into the sunset at the end of ST VI: TUC

Excelsior (in background) pursues Enterprise in ST III: TSFS

Excelsior sits in starbase, waiting for tomorrow's transwarp trials; ST III: TSFS

Note: Although the Excelsior and Enterprise-B are of the same starship class, they are NOT identical. The Enterprise-B (and USS Lakota, DS9: Paradise Lost) have been slightly modified with larger impulse engines, more sensors, redesigned nacelles and a weird skirt-like thingy on the bottom. Supposedly this was an improvement on the Excelsior design, but it actually had a use in ST: Generations. Since they did not want to create a whole new Enterprise model for about 15 minutes of footage, they decided to use the Excelsior model. Unfortunately, when the Enterprise-B hits the Nexis, the Engineering section sustains heavy damage. To allow for this, they added the above-mentioned stuff and called it an improvement. Now they could blast away all they wanted without damaging the Excelsior model (So they could use it in a Voyager episode I've forgotten).