“Set environment variables” [ edits will only take effect when a new command window is opened - they do not affect the current CMD or PowerShell session.

Environment variables are stored in the registry:

User Variables: HKEY_CURRENT_USEREnvironment
System Variables: HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession ManagerEnvironment

Machine variables are stored on the machine and will not follow a users roaming profile. To set a machine variable (/m) requires Administrator rights.

User variables are stored in the user profile and will follow the users roaming profile.

If variables with the same name are stored as both User and Machine Environment variables]