Does Modern Warfare include Warzone and vice versa?

If I buy Modern Warfare as a disc, will Warzone be there?

And if I download Warzone and then buy Modern Warfare, does that cost even more storage space? Because Warzone is already 100GB. (PS4)

Modern Warfare is the name of the game. Warzone is the name of the Battle Royale part. That is part of it. Like normal multiplayer or co-op mode.

You can also buy it for free if you don't have the main game. But that's just warzone.

In total, CoD is about 180 GB! The game also got a lot of big updates. But you can decide what you want to install and e.g. Leave out the campaign.

Yes and yes