Selling items online (through Facebook) to downsize.

I am retired and am downsizing.  I have many items that I'd like to sell to clear out my space.  There is a Facebook group set up specifically for buying and selling these items.  The payments are typically made through PayPal and will be sold for considerably less than I paid for them.  Will have I to pay taxes on this?  Would I have to pay taxes if I sold them on eBay?

Thanks!