I lived in the mountains of southern California for a while and I’d see rattle snakes all the time and they didn’t want anything to do with me and would either try to get away or make sure I knew where it was (shaking its rattle), so I’d walk around it.
There are hundreds of varieties of cobras but the most vicious is the King Cobra which has been recorded to be as long as 20 feet. Generally you need to stay at least five yards away from a King Cobra or you could be bitten. It’s not that its venom is so much more dangerous than other snakes but it has a lot of it and when it bites into something it injects a huge amount, enough to take down an elephant; maybe not kill it but take it out of commission for several hours.
The King Cobra isn’t known for running away but will instead rise up and if you don’t leave quickly, you might get bitten and die very fast. Snake charmers don’t typically work with King Cobras and the ones they do use often have their fangs and venom pockets removed; this is why they can get bitten so many times and still live.
The King Cobra is a venomous snake but not a poisonous one (same as rattlesnakes), which means it can be eaten. If a snake is in fact poisonous then it can be deadly to eat any part of its body or at the very least get extremely sick. By the way, I’ve eaten rattlesnake and it taste like chicken. :)