When I see something with yellow and black stripes flying toward me, my first instinct is usually to run away. You don't have to flee every insect by that description, though. It all depends on the species and situation, but wasps are generally the ones to beware more than bees.
Bees tend to be more docile than wasps, although both are known for fiercely defending their nests. Most bees can only deliver a single sting, whereas wasps can often sting multiple times. If you are unsure which is which, here are some ways to tell the difference between the two:
Bees tend to be pudgy, and they also have many hairs, making them look fuzzy. An extreme example of this is the bumblebee, and it's unlikely anyone would mistake a bumblebee for a wasp. Honeybees look a bit more wasplike, but they can still be distinguished by their fuzzy bodies. Wasps, on the other hand, have far fewer hairs and slimmer, longer bodies. There's a reason for this difference. Bees pollinate flowers as they seek nectar, and pollen sticks better to a fuzzy body. Many wasps are predators that feed on tiny bugs or larvae, and their body shape is more suited to predatory behavior. They can pollinate plants, too, although not as effectively as bees.
You can also tell the difference between bees and wasps by looking at the nest, if you can find it. Bee and wasp nests tend to be made out of different materials, so if you get a close look, you might be able to tell. Bee nests are made of wax cells (this is where we get "beeswax"), while wasps make their nests out of a papery substance. Bees tend to build their nest in tree cavities and other large spaces, while wasps tend to build their nest in smaller, more secretive spaces (like the corner of a window, under eaves or underground). Beware as you approach a nest, even if it looks empty.
For the most part, wasps are the ones to avoid. If you don't bother a bee, it's likely to leave you alone. If you're outside at a picnic, let it do its business among the flowers and you'll both be fine. Give a wider berth to wasps, however, since some species are more likely to mistake you for a threat.