The Black Mamba is a long, slender snake. They are usually light grey, olive or dark grey in colour, sometimes with mottling. They have elongated coffin shaped heads with dark eyes and the interior of their mouth is usually black in colour.
The Boomslang is a long slender snake, that has keeled scales, which give the body a rough appearance. Their heads are noticeably pointed and they have large eyes. Hatchlings and juveniles are grey with a massive emerald green eye but change to the adult colours around 1 m. Most males are bright green, sometimes with black between the scales (in the Cape Provinces they are usually black above with green, yellow or orange sides) Females are normally brown in colour.
It’s possible to confuse a Black Mamba with a female Boomslang. The graphic below illustrates how to recognize the key differences between the two species.