They're both poisonous snakes. They can both kill you. You want to avoid both at all costs.
That being said, the black mamba is the more perilous threat. It's venom is immediate and fast acting, and can kill you within an hour.
The copperhead venom could kill you, too. But it's slower moving and you can use that time to get an antidote.
Trump--as someone who is mentally unbalanced, highly impulsive and is currently the president--is the black mamba. He's the number one threat we have to deal with at the moment.
Pence--following in the wake of a Trump scandal--is the copperhead. He's dangerous and nasty but his power will be significantly weakened given the consensus that he's the fruit of a rotten tree, i.e. Trump. He'd also likely be less impulsive in terms of foreign relations and that's overall a better thing than what we have now.
Don't get me wrong. President Pence would be awful and we should resist his agenda just as much as we have with Trump. But the threat he poses is not as severe as what we are looking at with Donald Trump right now, so I'd rather grapple with that than with what we have to deal with at the moment.
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