The Sport Pilot Rule refers to "Special" Light-Sport Aircraft and "Experimental" Light-Sport Aircraft.
Although the FAA does not clearly distinguish it, there are two types of "Experimental" LSA.
The first type of Experimental LSA are the ultralights which undergo an inspection by a DAR and are transformed into an "Experimental Light-Sport Aircraft," which is a new category of "Experimental" under FAR 21.191. If you will allow me, I shall refer to this type of Experimental LSA as the "Former Ultralight E-LSA."
Although normally an experimental aircraft cannot be used commercially, a sport pilot instructor may instruct in a Former Ultralight E-LSA until September 1, 2009. After that date, a person may only fly a Former Ultralight E-LSA for his personal pleasure and may no longer instruct in it for hire.
Unlike the Former Ultralight E-LSA, the Kit E-LSA may NOT be used for commercial training. Only the Former Ultralight E-LSA may be used for commercial pilot training, and even the Former Ultralight E-LSA may only be used commercially until September 1, 2009.
Please note that a factory must build at least ONE ready-to-fly Light-Sport Aircraft before it will be allowed to deliver the light-sport aircraft kits.
The "Special" Light-Sport Aircraft (S-LSA) are the turn-key ready-to-fly aircraft manufactured in accordance to an industry consensus standard. The S-LSA does not have a normal aircraft type certificate issued under FAR 23, so that's why the airworthiness certificate which is issued to a light-sport aircraft will be a "special" airworthiness certificate, and not a "standard" airworthiness certificate.
The Special LSA (S-LSA) may be used for commercial training. After September 1, 2009 it will be the ONLY light-sport aircraft that can be used for commercial training. Because these LSA have a "Special" airworthiness certificate instead of a "Standard" certificate (such as a Cessna 150,) the ONLY commercial use of a S-LSA is for training sport pilot students. A S-LSA cannot be used for other commercial purposes, such as sightseeing, traffic reporting, fish-spotting, crop dusting, etc.
As stated in the Sport Pilot Rule, the last day that an ultralight instructor may teach in a two-seat ultralight trainer is January 31, 2008. By that date, if an ultralight instructor wants to continue teaching, he must obtain an FAA sport pilot instructor's certificate. He may teach in a Former Ultralight E-LSA until September 1, 2009. After September 1, 2009 he may only teach in a Special LSA.
In addition to Experimental Light-Sport Aircraft the Experimental Amateur-Built aircraft will continue to exist. The difference between an Experimental LSA and an Experimental Amateur-Built aircraft (E-ABA) is that an E-ABA does NOT have to conform to an industry consensus standard. Another difference is that the buyer of an E-ABA must construct at least 51 percent of the kit aircraft, whereas the buyer of an E-LSA does not have to build any specified percentage of the aircraft.
Neither the E-LSA or the E-ABA may be used for commercial flight training.
It is quite conceivable that a manufacturer may offer all three types of flying machines: Special LSA, Experimental LSA, and Experimental Amateur-Built aircraft.
Why would a manufacturer offer an experimental amateur-built kit in addition to an experimental light-sport aircraft kit? The reason is because the E-LSA is restricted to certain features whereas the E-ABA is not. For example, an experimental amateur-built aircraft may have more than two seats, may have retractable gear, may have an in-flight adjustable propeller, may have more than one engine, and it may weigh more than 1,320 pounds--all of which are not available to light-sport aircraft. Please note that if an amateur-built aircraft has any of the features mentioned above, it CANNOT be flown by a sport pilot. It could only be flown by a person with a private pilot certificate or higher. Also, the person who flies an experimental amateur-built aircraft must have an FAA medical certificate if the amateur-built aircraft has features that exceeds that which an LSA may have.