[chefross]

Enthusiasm, and motivation are both inherent traits. They can't be taught. Either you have it or you don't.
Some have it in varying degrees and call it "passion." Passion for something doesn't always translate into a good job work ethic.
There are pro's as JohnBD said who, when taken from their comfort, zone fall apart.
Then there are those who can walk into any situation and simply take over.
I don't believe a difference exists between the amateur and the pro. 50 years of dealing with people has been an eye opening adventure.

 

[chefross]

I had to go back and re-read the OP.
What's the difference between a regular cook and a highly enthusiastic amateur?
Nowhere was the word professional used.
You are assuming that a "regular" cook is a pro.
With enthusiasm, a Chef could train and re-teach an amateur. Re-training a regular cook, as retired baker mused, is difficult. Unlearning bad habits and relearning good is hard.
You can't teach enthusiasm or motivation. Either you have it inbred, or you don't.