London Overground Rail Operations was created in 2007.

The London Underground did give the East London line to the London Overground to ease its traffic.

it is neither in underground or overground. it is a separate system.

The track difference of the track layout of the London Underground and London Overground is whereas one is underground the other is over the ground.

Merseyrail Similar to London Overground in terms of how they operate since they all offer railway services to the people.