Yes, and getting more different. ICAO Document # 8643 defines “Super Heavy” (A-380) 1,200,000LBS MTOW or more, “Heavy” Above 300,000LBS MTOW “Medium” between 300,000 and 15,500MTOW, “Light” below 15,500MTOW.
The FAA’s “Pilot/Controller Glossary” defines only Heavy, above 300,000lbs MTOW, Large 41,000 to 300,000 MTOW and Small under 41,000MTOW. In actual operation, the FAA currently uses six (6) wake turbulence separation categories based primarily on weight: Super (A380), Heavy, B757, Large, Small+, and Small. In October 2012 a joint program was launched between FAA and Eurocontrol called “RECAT” revising wake turbulence categories to gain capacity. RECAT applies across the breadth of the current six wake-turbulence aircraft separation categories: super (A380), heavy (B757), large, small+ and small. RECAT will place aircraft into six categories labeled A through F for both departure and arrival separation. In addition to aircraft weight, the new categories will consider certified approach speeds and wing characteristics, along with special consideration given to aircraft with limited ability to counteract adverse rolls. The Airbus A380, for example, becomes a category “A” aircraft, while a Cessna Citation Mustang is listed as a category “F.” A Mustang following an A380 will be separated by 8 nm on approach under the new standards. FAA SAFO #12007, 10/18/12