In a shower head, there are pieces that slow the water and split up the spray. That way, people aren't blasted in the face by a thick stream of water at high pressure. More recently law in some places requires the shower head to throttle the rate of flow to conserve water.

There are efficient sprinkler heads, but they're not quite in same class, because the purpose of a sprinkler, after all, is to deliver a certain amount of water to plants. For most watering situations, the question is whether the right amount of water is being delivered to the correct area at the correct time. That sprinklers are adjusted, that the right sprinkler was chosen for the job, etc.

This North Carolina Water Quality & Waste Management doc covers the issues nicely, including mentioning that "Drip irrigation uses 30 to 50 percent less water than sprinkler irrigation and usually costs less to install."

It also notes that there is a place and time for hand watering with a hose. It specifies a nozzle that divides spray into rain-size droplets and using medium pressure for a minute. I.e., there's no attempt to use a head whose purpose is to conserve water, a certain amount of water needs to get to the plant, and that's all there is to it.