FAST FACTS:
The Black Mamba and the Green Mamba are both highly venomous snakes that can kill humans quickly with their fangs.
They are both elapids. Elapids are venomous snakes with fangs.
Black Mambas are olive or grey, and Green Mambas are shiny green.
Black Mambas are longer than Green Mambas.
Black Mambas are faster than Green Mambas.
Black Mambas are more venomous than Green Mambas.
Black Mambas like dry habitats, and Green Mambas like wetter habitats.
Black Mambas live on the ground and sometimes climb trees, and Green Mambas live in trees and sometimes crawl along the ground.
Black Mambas (Dendroaspis polylepis), Eastern Green Mambas (Dendroaspis angusticeps) and Western Green Mambas (Dendroaspis viridis) are all found in Africa. Eastern Green Mamabas are found in East Africa and Western Green Mambas are found in West Africa. They are all related, but they are different species.

Black Mamba

Eastern Green Mamba
Photographer: Martina Nicolls
Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM
how much more venomous is the black mamba than the green mamba
Great question.
Jeremy Seal in The Snakebite Survivors’ Club: Travels among Serpents (2000) and Wikipedia say that the Black Mamba is more venomous than other mambas in terms of its ‘size, aggression, venom toxicity, and speed of onset of symptoms.’ The Black Mamba (Dendroaspis polylepis) is terrestrial, living on the ground, whereas Green Mambas are arboreal, living in trees. Living on the ground means that the Black Mamba’s prey is mainly small mammals, whereas arboreal Green Mambas prey on birds. The Black Mamba bites repeatedly, and can inject ‘about 100-120 mg of venom on average, with symptoms showing ‘within ten minutes.’ The Eastern Green Mamba (Dendroaspis angusticeps) injects ’80 mg’ per bite and can be fatal ‘in as little as 30 minutes.’