Final answer:
John is reserved and introspective, while Lenina is outgoing and conformist.
Step-by-step explanation:
The essential differences in the natures of John and Lenina are that John is reserved and introspective, while Lenina is outgoing and conformist. John's character is depicted as traditional and conservative, while Lenina's character is portrayed as progressive and liberal. Additionally, John is shown to be obedient to societal norms, while Lenina rebels against them.