For those of you who don't know, in OS X 10.10 Yosemite, Apple (rather quietly) replaced what was formerly a "maximize window" button with a "make window full-screen" button - in previous releases, these were two separate buttons.
Currently, the window control button triplet looks like this when hovered over:
Whereas in past releases, the two, green, away-facing diagonal arrows would've been a plus sign, and the arrows would've been located at the opposite end of the window's toolbar.
Functionality-wise, the difference has been that the maximize window button would simply stretch the current window to the dimensions of the display; while the full-screen toggle window would slide the window over to a separate space (this allowed for multiple full-screen apps to run simultaneously; it resembles Windows 10's "virtual desktop" feature).
Was this design choice a good one, considering that maximize functionality seems to have been dropped completely (it doesn't show up in the Window system menu bar)?