What's the difference between a bee and a wasp?

Bees evolved from wasps, so the two insects are closely related.10 In fact, they are part of the same order, hymenoptera, which also includes ants and sawflies. There are quite a few similarities between bees and wasps: both can sometimes sting, both often sport yellow and black colours, both can be social or solitary, both are pollinators. Even experienced scientists can struggle to tell some species apart at a glance. 

However, there are a couple of subtle tell-tale signs that can help differentiate wasps from bees. Wasps are a little thinner and have narrower waists, often referred to as "wasp waist". And while they have four wings just like bees, theirs tend to be a little longer and when they fly, their two thin long legs hang straight beneath their body.13 Crucially, wasps tend to have a slick, bald hairdo, while bees are largely more hairy and fluffy – honeybees typically have almost three million hairs on their bodies – because fluff comes in handy when collecting and storing pollen.

While a bee's diet largely consists of pollen and nectar from flowers, wasps hunt other insects and lap up sugars from rotting fruits in addition to pollen.  Wasps sometimes eat bees too.