The biggest difference between the digital and physical version is that the digital version cannot be resold. it more likely buying a use right for specific user.

NFT + digital licence:
Set the NFT as an access token, and when the wallet holds this NFT, it can access the corresponding digital license.

Digital license’s pain point & solution:

• Not Resalable
  By transferring NFT, you can transfer the use rights.

• Unlimited published
  Add collectible attributes by limiting the maximum number of copies.

• Pirated
  Easily distinguish between pirated and genuine copies by checking the contract address.

Business Models:

The biggest difference is the royalty income from the secondary market, where publishers of physical and digital editions do not receive revenue from the secondary market.