Here's an early version of Cupid's pool, in King's Quest IV: The Perils of Rosella
, as seen in Sierra's InterAction
Notice the fountain in the upper part of the pool. In the final game there's no fountain there; instead, the north end of the pool is where Rosella can climb out if she's fallen in.
Here's the pool as it appears in the initial release (ver. #1.000.111, with green menu buttons) of KQ4 SCI.
Much of the background has been generally redrawn, including the small twin trees in the foreground.
Here's Cupid's pool as it appears in later releases of KQ4 SCI, which have different graphics (and white menu buttons).
Like many backgrounds in the game, it's been very notably altered from the original release. In this case, it's especially noticeable, because the two trees in the foreground are now gone!
Also note that the tree branch in the upper left corner is now depicted in shadow instead of being fully colored. In the later versions of KQ4, the art was altered so that the day and night versions of scenes could share art resources, which resulted in changes like this one. The original version of the game had included separate backgrounds of each location for day and nighttime.