What is the difference between ATL and BTL activities?

Above The Line – Marketing and advertising through mass-media, such as television, radio, newspapers, magazines, Internet, etc., which is less personal than Below The Line Marketing. Companies usually use advertising agencies for ATL marketing.

Below The Line – BTL. Describes marketing which has a short-term duration, such as non-media advertising, direct-mail, e-mail, exhibitions, incentives, brochures, etc., which is targeted directly at the consumer/customer. Often used by companies on a limited budget.