agent vs lethal agent

agent and lethal agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
agent	Yes	No	No	No
lethal agent	Yes	No	No	No

As nouns, lethal agent is a hyponym of agent; that is, lethal agent is a word with a more specific, narrower meaning than agent:

agent (noun)	lethal agent (noun)
the semantic role of the animate entity that instigates or causes the happening denoted by the verb in the clause	an agent capable of causing death
an active and efficient cause; capable of producing a certain effect
a businessman who buys or sells for another in exchange for a commission
a representative who acts on behalf of other persons or organizations
any agent or representative of a federal agency or bureau
a substance that exerts some force or effect