Do I Need to Report Ebay Earnings to the IRS?

This is a question that is often asked and so I googled around and found so many answers, many of them were contradicting.

Some said:
"Only if you made profit (so if you bought a dress for 2000$ and sold it for 200$, it's not profit)
If you make more than 400
If you make more than 600
If you make more than 800
Only if it's a business and not a hobby (but what defines the difference between a hobby and a business?)"
But which rumors ones are true?

I did a lot of looking up on the IRS website and these are the rules:
Question: What is the difference between an online auction (Ebay) business and a hobby (online garage sell)?
Answer:"If your online garage sale turned into a business and/or you have recurring sales and are purchasing items for resale with the intention of making a profit; you may have an online auction business"

1. If your auction sales are really an online version of a garage sale (things you sell from your household, and that you probably end up selling for less than you paid for), then you probably do not have to report the salesHowever, if these are appreciating items (items whose value go up over the years
2. If your auction sales are really a small business, you will have to pay tax fees.But you're also eligible for small business deductions! Go Here to find out what is deductible!
3. If you were using an online auction to sell off items of a current business (depreciating assets), you will have to report your earnings. You have to read this . It's a list of all the forms you could be asked to use.

FORMS:
Hobby: 1040 schedule D, line 13 IRS SITE
Small business: 1040 schedule C IRS SITE