First (thinner) is Windows ClearType, second is macOS Quartz. Both are screenshots of the Imperial (NYT) font on Chromium.
Personally, I prefer the Mac grayscale antialiasing. Windows’ fringing and freakish devotion to cramming everything into a neat pixel grid always looked wrong to me. https://hachyderm.io/@samhenrigold/113501076364481804
@samhenrigold I like macOS’ rendering better too. FreeType on Linux as configured in Ubuntu and Fedora look pretty similar to macOS rendering (though antialiasing and hinting are more tweakable there).
ClearType’s aggressive pixel snapping made more sense back when really bad low resolution LCDs were common (low pixel density == hard to read with mac style rendering) but these days even cheap laptops have ok-enough screens that it’s not really necessary.