Having panicky thoughts about Facebook potentially buying an army of drones? Stop. Breathe. And remember: All drones are not created equal.

Most people think of drones -- pardon, unmanned aerial systems -- and their military applications, but Facebook's possible acquisition and Amazon's plan to use them as our friendly neighborhood delivery bots  stand as good reminders that there are many kinds of drones out there, and they're subject to different regulations.

According to TechCrunch, Facebook is looking to drones to help it fulfill its mission to wire the parts of the world that still aren't connected to the Internet  -- the company has declined to comment on rumors or speculation. The unmanned systems in question are made by Titan Aerospace and are meant to fly way up in the atmosphere to provide Internet connections to rural or undeveloped areas. They can carry a payload of up to 25 pounds and can stay in the air for up to five years.

By comparison, the "octocopters" that Amazon chief executive Jeff Bezos has talked about are lighter and smaller and fly much, much lower. As you can probably guess from the name, they have eight rotors. While the Titan Aerospace drones  can fly up to 65,000 feet, the delivery bots from the Amazon fleet are meant to zoom closer to a human scale and can go a distance of about 10 miles with a five-pound payload, as The Washington Post reported.

Amazon faces regulatory restrictions to fly its UAS's -- because regulators will want to keep track of how all those copters zip over buildings and homes and set safety rules about what those drones can and cannot do. They'll also want to take precautions to make sure the drones aren't flying into things and are insulated against being taken over by hijackers.

Those regulatory concerns aren't quite as important to Titan Aerospace because its drones may fly above zones that the FAA regulates -- though launching them may be a more complicated regulatory issue, if done over the United States. Once they're up in the air, however, they could reach places that may not be regulated by the United States, said Cameron Cloar, an aviation litigation attorney at San Francisco's Nixon Peabody.

"These aircraft may present new regulatory issues for the FAA that it's not had to deal with before," he said.

The FAA estimates that there will be 7,500 in the United States by 2018, but you shouldn't expect to see your pizza delivered by UAS any time soon. Cloar said that commercial use of drones in FAA space is farther down the agency's list of priorities, meaning ideas such as the plan that Amazon has posed or Nokia Here chief Christof Hellmis's dream of using mapping drones won't come to the United States until the government has gathered data from its UAS test site and opened airspace to the public sector for testing.

For now, the FAA must approve commercial drone use on a case-by-case basis, as it did for ConocoPhillips last year to allow the firm to conduct research in the Arctic Circle.

(Disclosure: Amazon chief executive Jeff Bezos is the owner of The Washington Post.)