What is the difference between concurrency and parallelism?

Concurrent ： Two or more events occur at the same time interval .

parallel ： Two or more events occur at the same time .

Parallelism is really , Do many things at the same time , Concurrency can only do one event at a time , It's just that you can chop up time , Do many things alternately .

There is an example on the Internet, which is very vivid ：

You eat half of your meal , Here's the phone , You don't pick up until you've finished eating , This means that you don't support concurrency or parallelism .

You eat half of your meal , Here's the phone , You stop and answer the phone , After that, continue to eat , This means that you support concurrency .

You eat half of your meal , Here's the phone , You're eating while you're on the phone , This shows that you support parallel .