Reasoning

All except Potato are fruits, while potato is a vegetable.

All except Grasslands are types of grasslands.

All except Vijayawada are capitals of states of India.

All except Eagle are flightless birds.

All except Puppy are names of animals, while puppy is a young one of dog.

All except Bevin were the Prime Ministers of UK, while Bevin was the Foreign Secretary of UK.

All except Disco are folk dances.