There is actually a large difference between something being poisonous and something being venomous
Not only that but there are different types of venom in this world that all act different in our bodies.
What makes these different?
Well For starters something that is poisonous has to be ingested, inhaled or delivered by touch.
An Example of Poisonous plants are Hyacinth
These beautiful plants deliver the poison if you touch or digesting the bulb of the plant, the symptoms of these plants is vomiting, nausea, diarrhea and can be fatal.
An Example of a poisonous animal is The Poison Dart Frog
These frogs get their names from the amazonian natives that use the poison that is excreted from their skin of these frogs and smear it onto their darts to take down prey.
Ok so then whats the difference from venomous?
Well, for something to be venomous it needs to be injected into a wound. What makes venom so different to poisonous is that it isn't actually poisonous. Meaning that it generally wont actually hurt you if you ingest it or touch it.
So what creature is venomous ?
Anything that needs to inject you with its venom ofcourse
Like the Black Mamba
A creature native to my beautiful country of South Africa.
I hope you learnt something with todays TIL, If you enjoyed it or learnt something please follow me 
@warrensteem
Sources :
http://aggie-horticulture.tamu.edu/earthkind/landscape/poisonous-plants-resources/common-poisonous-plants-and-plant-parts/
http://www.conservationinstitute.org/10-most-poisonous-animals-in-the-world/
https://en.wikipedia.org/wiki/Poison_dart_frog
http://www.todayifoundout.com/index.php/2012/05/the-difference-between-venom-and-poison/