Fast and Quick are similar words to say "high speed" with different perspectives(角度), it’s difficult to tell differences between them if without a specific sentence context(上下文环境). In many cases, these two words can be interchangeable(可交换的).
Fast refers to things that go or happen at high speed, It’s both an adjective(形容词) and an adverb(副词).
Fast 快速，速度很快，发生的很快的意思。
Examples:
You run very fast, I can’t catch up you.
你跑的太快了，我跟不上。
The High-Speed Train run very fast.
那个高铁跑的很快。
This is a fast (Quick is wrong) car.
这是一辆跑的很快的车。
Don’t eat fast (quick is wrong) food so frequently. It has nothing help for you.
别经常吃快餐，对身体没好处。
Quick refers to something that happens in a short time, or a shorter than expected time.
It is an adjective (形容词) and its adverb(副词) form is “quickly”.
Quickly means that something which is done fast.
Quick 用时短暂的意思。指一件事持续时间很短，或者比期望的用时短的意思。副词quickly是动作快的意思。
Examples:
Please give team a quick (fast is wrong) answer because of insufficient time left.
时间不够了，请快速给大家一个答案(快速是因为答案简短)
We should do it quickly. (to finish it with less time)
我们应该加快速度(目的是用较少的时间)
Let’s have a quick (fast is wrong) discussion before attending the meeting.
开会之前咱先短暂讨论一下。
