If you're familiar with console versions, it's the same idea: themed packs changing up the appearance of mobs and blocks in the game. For example, the Switch version of Minecraft comes with the Super Mario Mash-Up Pack. Because of this, it has content packs you can buy to shake things up, and different versions include different themed-content. The Windows 10 version of Minecraft is technically a 'Bedrock Edition' of the game, which is an iteration of the now-discontinued 'Pocket Edition.' Pocket Edition was the mobile version of Minecraft that went on to be the foundation, or bedrock, of the current multi-platform editions of Minecraft.
