So there’s not much of a difference.

If Google’s superior readability isn’t on account of fewer labels, then what else explains it? If you look closely at Google Maps, Google seems to employ a number of unique effects...

1. THICK, WHITE OUTLINES (THAT OBSCURE ALL BACKGROUND DATA)

I can see you thinking it now: “Wait, doesn’t Yahoo! Maps also have white outlines around the text of its city labels?” Yahoo! certainly does—but there’s a key difference: Google’s outlines are thicker, and you can’t see the map’s background details (e.g., roads, rivers, etc.) behind them.

For instance, look here at Google’s “New York” label. Notice how you can’t see any roads or other details behind the “N”, the “e”, or any of the other letters: