to differentiate between boomslang snakes and bush snakes are,for one,they have different heads:
this is a boomslang snake head
and this is a bush snake's head
you can clearly notice the difference between the size and style of the heads in the snakes' heads.
so for two,you can see once again ,that the boomslang snakes do not have a lot of spots on it's body.So, it is clearly stated that it is not a venomous boomslang, but just a harmless little bush snake.
even though most of the snakes in the world are venomous (or poisonous), it doesn't mean that we should kill them.You see,snakes help to maintain the ecosystem.Besides,snakes kill rats,so we would not want a pest city.Always remember,snakes do not harm you,unless you harm them.
always know your snakes,so you will not get into trouble with the snakes.
'till then,Stay safe ,and Have fun