Mac vs Windows pc for Unity game devlopment
Unity is great tool for creating 3d and 2d games. If you are thinking which pc you should use for unity so you can use any OS because unity is a program which have properties and functionalities to run.
Unity is a quit heavy software so you choose a high performance cpu, and 8 GB or more RAM.
Unity work smoothly in both OS mac and windows. All features are same. When you are creating a game, game will only depend on scripting, UI and other unity tools rather then on which OS running unity. Both OS have same core engine and C# scripting. OS only matter for what platform you are creating games
MacOS importance
Mac is only important If you want to publish your game to Apple App Store then you must have a mac for uploading your game to their store. You can not publish your game to Apple App store if you don't have a mac. In all other cases both OS are amazing.