Timestamp navigation:
( 00:00 ) ペンギンうきうき びっくりすいぞくかん めいろ・パズル in process of being converted to US version, "Pepe's Puzzles", prototype dated 1995/02/10 (Labeled "Pengin Ukiuki Bi Kkurisuizokukan Meiropazuru Rev 19959210 (1994)(Sega)(JP)(beta)" in TOSEC)
( 04:10 ) 2nd localization prototype with glitched title screen palette,1995/02/18 (Labeled "Pengin Ukiuki Bi Kkurisuizokukan Meiropazuru Rev 19950218 (1995)(Sega)(JP)(beta)" in TOSEC)
( 06:52 ) Third localization prototype with altered audio, dated 1995/02/20. (Labeled "Pepe's Puzzles Rev 19950220 (1995)(Sega)(beta)" in TOSEC)
( 10:30 ) Final prototype that appears to be same as final, dated 1995/02/24. (Labeled "Pepe's Puzzles Rev 19950224 (1995)(Sega)(beta)" in TOSEC.)
( 12:40 ) Final version.

Combining the work of the Hidden-Palace prototype release and Team-Europe's retail ROM dumps.
http://team-europe.blogspot.com/

Among the big proto batch was a set of four ROMs labeled as such:

Pengin Ukiuki Bi Kkurisuizokukan Meiropazuru Rev 19950210 (1994)(Sega)(JP)(beta)
Pengin Ukiuki Bi Kkurisuizokukan Meiropazuru Rev 19950218 (1995)(Sega)(JP)(beta)
Pepe's Puzzles Rev 19950220 (1995)(Sega)(beta)
Pepe's Puzzles Rev 19950224 (1995)(Sega)(beta)

As it turns out, all of them are actually work-in-progress localization prototypes for "Pepe's Puzzles", which worked on changing the text and the voices. This video takes a quick gander into the changes.

Probably the most notable visual detail is the way the title screen and Pico logo change between prototypes - otherwise not much else changes visually.

Audio-wise, there's a set of English voices right from the start, but for whatever reason they get changed during the 3rd prototype.

1995/02/24 looks at first glance to be the same as the final release, although I didn't check deep enough to verify that.