You’re right, and that’s why I think Carolina shouldn’t be an older vessel but rather one from Enterprise’s own generation. It should look noticeably like her in most ways. But I don’t think that means the same size saucer, nacelles, secondary hull, etc. And I don’t think general looks necessarily equate to equal function, though there is where interpretation comes into play. Somebody designing for a TV show would probably disagree on that point.
My point is, Enterprise goes beyond the frontier, comes back to base, goes beyond the frontier, comes back to Vulcan, goes beyond the frontier, etc. It has speed, endurance, range, and defensive capabilities. When it is back at Capella, it is in contested space where military vessels are policing space lanes for ships like Diedre. THAT’S what I take Carolina to be. Enterprise can do that job, and does, but not as its primary task. It is more capable than that. When she is out in unexplored space meeting Balok, there is no Carolina - or anything like her - anywhere around.
My point is, Enterprise goes beyond the frontier, comes back to base, goes beyond the frontier, comes back to Vulcan, goes beyond the frontier, etc. It has speed, endurance, range, and defensive capabilities. When it is back at Capella, it is in contested space where military vessels are policing space lanes for ships like Diedre. THAT’S what I take Carolina to be. Enterprise can do that job, and does, but not as its primary task. It is more capable than that. When she is out in unexplored space meeting Balok, there is no Carolina - or anything like her - anywhere around.