What is the difference between “venom” and “poison”?
Both in usage and in meaning.
Poison is contextual and can be an artificial or natural material -- different materials can be poisons to different organisms in different doses and/or when misused. Further, poison usually denotes potential fatality.
Venom is a material created and used by an organism to aid in defense and/or hunting. Venoms are not necessarily fatal -- many stun, sting, or disable. Venom is venom regardless of context, and can also be poison in some contexts.
Both words are used heavily in metaphor. Poison is often used to describe something that corrupts, destroys, or has the potential to do so, usually over time -- an eventuality. Venom is often used to describe harsh speech or hurtful aggressiveness.
Venom is a toxin that is harmful only when it enters the bloodstream, produced by animals of various species.
Poison is a toxin that is harmful when ingested (and, in more general terms, however it gets into the system). It is also a catch-all term for any harmful substance.
Thus there are many venomous snakes, but very few poisonous ones, i.e. ones you would have to eat for them to harm you.
Venom is contained by a living organism, and it is often used as an offensive/defensive measure to ensure survival. Venom is often poisonous to the intended target.
Poison is an item that is harmful or dangerous to the person/thing to which it refers.
Venom is used to refer to the poisonous substances that animals like snakes and scorpions produce.
Poison is used to refer to substances that could harm or even kill somebody through its chemical action.
To illustrate the difference, consider this article: Poison, not snake, killed Cleopatra, scholar says
The article says that Cleopatra may have "died from drinking a mixture of poisons and not from a snake bite." The snake bite would release venom. But Cleopatra drank something to kill herself - that's poison.
This other article explains the same as: Cleopatra Died From Poison. She used hemlock, not snake's venom, says historian
You have some good definitions, but I will add a bit of usage.
When someone has been struck down by a venom- the bite of a venemous animal, or venom on a blade, they have been poisoned.
When someone has ingested something poisonous they have been poisoned.
Although technically incorrect, people often talk about snakes being poisonous, by which they mean venomous.
Venom is a word that is less commonly used now.
In that respect in day to day usage you can get away with using "poison" when you might be more technically accurate to use "toxin."