The first Freddi Fish was originally intended to be made in DOS but Ron Gilbert went to a conference and saw some examples of hand drawn animation and decided to scrap the DOS version halfway through and redo all the art and animation with the new hand drawn method.
This screenshot consists of Freddi and Luther talking to Grandma Grouper. There are quite a few minor differences going on here:
The most obvious difference is that Grandma Grouper is smiling instead of worried in the pre-release image. There is a possibility that this was done for marketing reasons though; it's not exactly presentable to have a frowning character advertising your game.
Freddi is considerably higher up in the pre-release image and Luther's upper fins are far shorter.
While extremely hard to notice, two very tiny graphical differences are also present across these two screenshots. In the pre-release version, there is an area above the fence that is blue instead of black and a slightly brighter highlight on a brick in the final. The blue wire on the clock also got a few pixels of shading.
This is a shot of the opening scene where Sam gives Freddi some flowers for Grandma Grouper. There are a surprising amount of differences here:
Sam is a few pixels higher up in the pre-release version, he's holding the flowers at a different angle, and there is some shading under his feet that did not make it to the final.
The buoy was partially redrawn in the final. It got a shine effect, it was extended to the left a bit, and the circle on top got some dark shading in the center.
The water has a noticeable reflection effect going on in the pre-release version. This was removed in the final. On a similar note, Freddi also has a lot more ripples around her. In the final, these only appear when she initially pops up.
The mountains in the background are blue instead of green.
This is a demonstration of Mr. Starfish's math minigame. This one has the most differences:
For some odd reason, both Freddi and Mr. Starfish are (or appears to be) talking at once. This cannot happen in the finished game.
Mr. Starfish seems to have been re-animated in the final game; no similar frames exist to the one seen in the pre-release screenshots. He has a pink tongue instead of a red one, he points at a different angle, and his bow tie looks more primitive in the pre-release version.
The font used for the numbers is slightly different.
The numbers are considerably higher in the pre-release version. They were likely moved down to give Mr. Starfish an easier time pointing at both parts of the equation.
The unused skeleton click point is present in this screenshot. As mentioned on the main page, the final game lousily erases over it with another graphic and it leaves an odd cutout in its place.
The Stop button is missing in the pre-release version.
The pre-release version seems to use stars to indicate the number of correct answers. The actual game simply does it through dialog.
The background got a major overhaul in the final game, now visibly showing the junkyard. This may have been the result of the junkyard being located somewhere else, as the clock is still present on the first screenshot.
Some more rock was added to the bottom of the screen as well, giving a place for a purple sea urchin. This also led to the erasure of the plants that used to be there. Also, a guide arrow was added to point to the junkyard.