This is the original art submitted by Alex Horley-Orlandelli, but the cow's expression was thought to be a little too cartoony.
This second version shadows the cow's expression and also moves the Giant farther away to make it look less like a creature card.
Now let's look at one that's a little more subtle: Hillcomber Giant!
In the original art by Ralph Horsley, the giant's a little bigger than a 3/3. See that cow on her belt? She must be huge! The creative team called this “giantflation”—the tendency of giants to look too giant.
The cow has been replaced by a goat, shrinking her down to an acceptable size. Her face has also been tweaked, making her less "ogre-y".
Finally, Warren Mahy's Lairwatch Giant required an almost total rework:
The original version seemed a bit more glum than watchful. Something had to be done to jazz him up and give him some purpose.
That's better! Now he's standing up, ready for action. "Come get some," he seems to be saying.