Rate is usually expressed in percent while unit rate is expressed as an amount of money or miles, or some other measure. Unit rate examples are miles per gallon, cost per kilogram, miles per hour, children per family, etc. Rate examples are mortgage rate, interest rate, tax rate, hire rate, heart rate, overtime rate, sales tax or purchase tax, value added tax (VAT), etc., but can also refer to speed, as in miles per hour. So some rates are actually unit rates. Unit rates usually involve at least two quantities like cost per kilo of bananas (fruit, money and weight), cost of fabric per foot or metre (material, money and length), carpet per square foot (material and area), cost of milk per pint (consumables, money and quantity), where one of the quantities is one unit like one pound, one gallon, one foot, one square yard, hence the use of the word "unit" in unit rate. Shops will often display price per kg on items like meat where pieces of meat are different weights and therefore are priced differently, so that shoppers can compare prices by comparing unit rates. Unit rates are good for making comparisons so that you can pick best value for money from a range of differently priced items,