You will get Minecraft Java and Bedrock Bundle MS Store Game Key. It will give you both games from 1 game key.
Notes:
1) Please check that your MicrosoftStore app opens before placing an order, some people have problems opening it. You can try updating or resetting the app in such a case.
2) Minecraft Bedrock is not available for MacOS so you cannot play it on MacOS but it will still be available in your account, Bedrock can be played on Windows PCs only.*
Some general reasons why game keys are a better option overall:
1) Online game modes work
2) One-time purchase for the whole lifetime game.
3) Redeem in your own personal account
4) Full control over account