You're right that it's opt-out with Microsoft and opt-in with Apple. However Microsoft's opt-out screen appears during setup before you ever even reach the desktop. Where as Apple's opt-in is a nag that occurs periodically as you use the device or anytime you install an update.
I understand that Apple has publicly disclosed how they anonymize data and roll identifiers but Microsoft hasn't so you really can't say if telemetry data can be tied back to a user or not because you don't know.
