Wasps and honeybees are both insects. But the main difference between both of them / them is that when wasps sting, they don't die.
Thank you so much for spending your time to answer my question.
"both of them" is wrong. "When wasps sting, they don't die" is not a difference between wasps, and nor is it a difference between honeybees. It's a difference between wasps and honeybees. The only time you should say, "They are both different" is when two things are both different from a third thing.