Hello, a dumb question, I am aware that prefect Parameters are used to define flow inputs. What would happen if I use python variables that were defined out of the flow instead of define Parameters and adding the variables in flow.run?

You lose the ability to define them when the flow is executed in different ways (e.g. triggered by an Agent on a schedule or through the web UI)

So, for a Prefect core user, it makes no differences?

I don't feel confident saying there are no other differences, but that was one I could think of!

Even if you run it locally, using Parameters makes it easy to replace the parameter values at runtime without having to implement any argparser e.g.:

flow.run(parameters=dict(x=2))

or CLI:

prefect run -p parametrized_flow.py --param x=3

This post dives deeper into the topic if you're interested https://www.prefect.io/blog/how-to-make-your-data-pipelines-more-dynamic-using-parameters-in-prefect/

This actually makes me stick to Parameter, thanks!