From the tax-collecting perspective of the United States Internal Revenue Service, the preponderance
of these differences may help to characterize one's craft production as either a "HOBBY" or a "BUSINESS":

Business Crafting

You have a reasonable expectation of making a profit.

You invest significant personal time and effort. You depend
on the resulting income of the activity. 

Your expenses are ordinary and necessary to run your business.

You have a track record or reputation in this industry, and/or a history of making profits. 

You have multiple customers or professional clients.

You maintain professional records, including a separate
checkbook and balance sheet; you have business
cards, stationery, and your own branded
business website.

Hobby Crafting

You may sell occasionally, but making money is not your main goal.

It’s something you do in your free time; you earn the bulk of your money elsewhere. 

Your expenses are driven by your personal preferences and not strictly necessary. 

You don’t have professional training in the field and have rarely or never turned a profit. 

You have a few customers, mainly relatives and friends. 

You do not keep strict professional records of your
activities; you also do not have a formal business
website or business cards.