I promise I could tell the difference if you are feeding the same signal into both and it features anything < 100hz.
The MBP speakers are nearly impossibly good, but they are not and never will be a match for dedicated studio monitors, pro audio, home theater, or even DIY contraptions. There are fundamental physical limits to how far this suspension of disbelief can be taken. We are pretty much at the limits of this trickery right now.
That's rather hyperbolic. I think superlatives such as "fantastic" and "extremely good" should be reserved for stuff that's truly exceptional. I have a 14 inch M1 MBP and yes, the speakers are surprisingly good for what they are, but comparing them to monitors tells me your love for this product is clouding your judgement. Or that your hearing isn't all that great.
I'm not sure if the 14" sounds the same, I've never heard it.
Anyway, these speakers are the first laptop speakers where I don't hear any obvious distortions. I haven't done any listening tests, but subjectively these speakers feel closer to monitors (at low volume) than to other laptop speakers.
I don't know how they are doing it, but listening to those speakers seems unreal. I opened the Macbook to look at them, the speakers look pretty big and they seem to have a long resonance channel, and I think they are glued to the aluminium chassis which appears sturdier than any previous Mac I've opened.
They are optimized to sound best when you are sitting in front of your laptop, and the volume is of course limited, but there is nothing "cardboard box" like about the new Macbook Pro's speakers.