LED bulbs or LED downlight?
Difference is in light footprint. Think of down-light like a spot-light. 

LED Bubs are more intended to act more like.. well .. bulbs. That is, be non-directional. Down-lights will make a bright spot on your floor.

Generally the bulb type is more popular because people are trying to replace standard bulbs in standard fixtures. 

However if you are replacing a bulb in say a pot-lamp, it makes more sense to use the down-light since you get more light coming in the direction you need for the same wattage.