[wwbirds]

People should probably phrase "shooting clay birds" instead of describing shooting skeet or trap which invokes a certain set up in experienced shooters.
As elk stated trap is shooting clay birds primarily thrown away from the shooter from one station or thrower whereas skeet is a variety of stations in a semi circle between 2 clay bird launching houses one throwing high birds and one throwing low birds. Ideally skeet guns are designed to break clay at 22 yards while trap birds are frequently broken at considerably longer distances and often require tighter chokes. Sporting clays is often a combination of both and additional challenges such as rolling rabbits, mini clays etc.
Shooting clays in a field is great practice for wing shooting and some throwers even can throw doubles for more experienced shooters but cant really compare to trap skeet or sporting clays which have formalized rules and set ups.