I would imagine that the Miranda-class (at least that particular variant) might be more specialized toward combat than a Constitution-class, given with the added phaser cannons and aft torpedo launchers. The Connies were pretty heavy on scientific, diplomatic, and exploratory missions in addition to combat and so might be a bit more generalized. However, while the Miranda might have a few combat-specialized perks I'm guessing the Connie had more overall power, longer range, and probably more torpedo casings to launch through fewer tubes.
I was actually just thinking along the same lines that the Miranda
seems to have many different applications over the years, from unarmed transports to Sisko's scientific Saratoga
to apparent power-hitters such as Reliant.
So that is important to keep in mind.
Still, it seems like one Miranda
can only do one thing well at a time - i.e. the variants I mention above - but that the Constitution
is a generalist - jack of all trades, master of none. But I agree that the Reliant
is probably generally less powerful and less well-equipped, even if it might be specialized for tactical outings.