Learn something new every day. I won't even bother to respond to the specifics of your comments, but thanks.
A laptop at 1440 and a 24" at 1920 do not even remotely have the type of difference/effect I'm talking about when viewing designs between the two; they look identical. I don't why I'm supposed to automatically know the difference when talking about a 27" and 24" iMac when they look nothing alike.
The physical dimensions of images on the higher res display will always be visually smaller than they will on a lower resolution display. Here's a way to see this side by side: go to the Apple Store, place a high-res 15" MBP with a standard MBP and look at the lettering on the title bar. Compare web site type on the same site. The high res MBP will show items smaller.
If you want to see pixels at the same size as your 24" iMac, run your 27" at the me resolution by adjusting your Display settings in system prefs.