flink
quick / nimble
Moving quickly, skillfully, and nimbly.
Das flinke Eichhörnchen kletterte in Sekundenschnelle den Baum hinauf.
The nimble squirrel climbed up the tree in seconds.

quick
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quick / nimble
Moving quickly, skillfully, and nimbly.
Das flinke Eichhörnchen kletterte in Sekundenschnelle den Baum hinauf.
The nimble squirrel climbed up the tree in seconds.

The word 'flink' (quick/nimble) has an entirely positive connotation. It describes not just pure speed, but also skill, agility, and a certain lightness.
Mit ein paar flinken Handgriffen hatte der Mechaniker das Problem gelöst.
With a few quick, skillful movements, the mechanic had solved the problem.
You can tell from context whether 'flink' (quick/nimble) refers to physical or mental speed. If it refers to movements, animals, or body parts, the physical meaning is intended. If it appears in connection with thinking, calculating, or the mind, it refers to the mental meaning.
Das flinke Kätzchen jagte der Maus hinterher.
The nimble kitten chased after the mouse.
In its physical meaning, 'flink' (quick/nimble) is often connected with agile movements and body parts. Typical combinations are 'flinke Finger' (nimble fingers), 'flinke Beine' (quick legs), or the expression 'flink wie ein Wiesel sein' (to be quick as a weasel).
Die Pianistin hat unglaublich flinke Finger.
The pianist has incredibly nimble fingers.
To express mental quickness, 'flink' (quick/quick-witted) is often combined with the mind or mental abilities. Common expressions are 'einen flinken Verstand haben' (to have a quick mind) or 'flink im Kopf sein' (to be quick in the head).
Er ist flink im Kopf und versteht komplexe Zusammenhänge sofort.
He is quick in the head and understands complex connections immediately.
fast / quick
'schnell' and 'flink' can both mean that something happens at high speed. 'schnell' is the general word and fits almost anything: a car, an answer, a task, or a movement. 'flink' is used more for people or animals when they move quickly and skillfully. It can also mean that someone understands quickly or is mentally alert. The words can be confused because both express speed. As a practical rule: 'schnell' is neutral and very broadly usable, while 'flink' additionally emphasizes skill or a nimble reaction.

Clara ist in der Küche flink und schneidet das Gemüse in wenigen Minuten.
Clara is quick in the kitchen and cuts the vegetables in just a few minutes.
In der Pause liest Max schnell die Nachricht auf seinem Handy.
During the break, Max quickly reads the message on his phone.