on sale is discounted price and for sale is the availability to be bought
Sales:-In general sales means good sold by you.In other words quantity that has been sold to your customers.Sales Turnover:It means number of times your able to sell the goods in market.
They literally mean the same thing.
Cake sales normally have Cake and Cupcakes and Bake sales have Bread and stuff related to bread (things that are baked mostly)
Rate requires that you calculate the growth over time. I grew 10% (Yippee!) ...after operating 50 years (D'oh!).