It's been a few years, but:

Consignment: You set the price for the item. Assuming it sells, you get paid after 30 days less HRO's commission. I don't remember the percentage they get, but somewhere around 20% sounds right.

Trade: You typically lose your shirt. Not necessarily meaning they're thieves, but you have to remember they can't sell it for more than fair market value, so you will get significantly less than fair market value.

You are always better off trying to sell gear yourself, IMO.

BTW, I don't think this is just typical for HRO. Most ham dealers will do the same.