Hi! I'm still checking the comments, and thanks for your question.
Gameplay-wise all versions of the game (the free rom available here or the two different physical editions) are identical. Their only differences are related to the publisher logo screen and / splash screen:
- The free rom available here has a "Catskull" logo screen and the word "Free Rom version" on the title screen.
- The physical release by Catskull also have the same "Catskull" logo screen, but doesn't have the "free rom version" mention on the title screen. This one was only available as "cartridge only", and is out of print since several years.
- The physical release by Yastuna Games have a "Yastuna Game" logo screen, and the same title screen as the Catskull physical release, without the "free rom version" mention. This edition is still available from Yastuna Games, as cartridge only or complete in box (or even as "box only" for those wishing to update the catskull release to a complete version). More info here: https://yastuna-games.com/en/nintendo-game-boy/52-65-sheep-it-up-gb.html#/28-gb_...
Don't hesitate to ask me if you need more details / info!