Regarding the name of the Defiant, in the trope "The Nth Doctor" (warning: a bit of stream-of-consiousness follows):
Defiant was not sequentially named (i.e. Defiant-A) after the ship from "The Tholian Web" because it was a ship of a different class/mission.
The various Enterprise ships were, basically, exploration ships, thus each succeeding ship was incremented (-A, -B, etc.). Plus, they all shared a common registry (NCC-1701).
Note also that the "original" Enterprise (Kirk's ship) was at least the eleventh ship to bear the name, following seven U.S. Navy ships, the space shuttle prototype, the sub-light ship (shown in the title sequence of Star Trek: Enterprise), and the NX-01.
Several of these earlier ships are shown in paintings/sketches in the first movie (in the recreation room scene) and in Star Trek: Enterprise (in Archer's ready room).
The original Defiant was a Constitution-class ship, just like the "original" Enterprise. The DS-9 Defiant is a warship, a new class of vessel. Also, as noted in the trope, the original Defiant was a prototype, while the second was a production model, with a different registry number.
Real Life equivalents are the P-47 Thunderbolt (a fighter repurposed as a ground-attack aircraft) and the A-10 Thunderbolt II (designed as a ground-attack aircraft). Same mission, sequential names. Compare with CV-14 USS Ticonderoga (an Essex-class aircraft carrier) and CG-47 USS Ticonderoga (nameship of a class of guided-missile cruisers). Different missions, non-sequential names. Note also that there were three previous ships in the U.S. Navy named Ticonderoga, all with different missions.
Money can't buy happiness, but it can let you rent it for a while...
Regarding the name of the Defiant, in the trope "The Nth Doctor" (warning: a bit of stream-of-consiousness follows):
Defiant was not sequentially named (i.e. Defiant-A) after the ship from "The Tholian Web" because it was a ship of a different class/mission.
- The various Enterprise ships were, basically, exploration ships, thus each succeeding ship was incremented (-A, -B, etc.). Plus, they all shared a common registry (NCC-1701).
- Note also that the "original" Enterprise (Kirk's ship) was at least the eleventh ship to bear the name, following seven U.S. Navy ships, the space shuttle prototype, the sub-light ship (shown in the title sequence of Star Trek: Enterprise), and the NX-01.
- Several of these earlier ships are shown in paintings/sketches in the first movie (in the recreation room scene) and in Star Trek: Enterprise (in Archer's ready room).
- The original Defiant was a Constitution-class ship, just like the "original" Enterprise. The DS-9 Defiant is a warship, a new class of vessel. Also, as noted in the trope, the original Defiant was a prototype, while the second was a production model, with a different registry number.
- Real Life equivalents are the P-47 Thunderbolt (a fighter repurposed as a ground-attack aircraft) and the A-10 Thunderbolt II (designed as a ground-attack aircraft). Same mission, sequential names. Compare with CV-14 USS Ticonderoga (an Essex-class aircraft carrier) and CG-47 USS Ticonderoga (nameship of a class of guided-missile cruisers). Different missions, non-sequential names. Note also that there were three previous ships in the U.S. Navy named Ticonderoga, all with different missions.
Money can't buy happiness, but it can let you rent it for a while...