"Sparring" is taught and trained as "A.O.T. or D. Depending upon the lessons. Anticipated Offensive Training Techniques, and Drills.
Mr. Parker always said Self defense techniques are designed primarily for when you are attacked momentarily unaware. You look up to see a punch coming, or you're pushed off balance before you know it.
There is supposed to be another set of techniques and drills to draw the forms sets and techniques together to complete the circle of learning tools. You'll notice that 'sparring' isn't mentioned. Most "sparring' by its very nature is a limited extemporaneous exchange for the purposes of scoring points in competition. t is therefore very limited in application, and even they are supplanted with 'scoring' over proper form, technique, and body mechanics. This type of sparring is counter-productive and usually ends up looking like two unskilled guys brawling, instead of trained fighters training.
"Freestyle" was created to be a sport for competition,and is the lowest form of expression of the martial arts, and rarely does the ability to "freestyle spar" translate into the ability to fight equally as well on the street.
A.O.T. fills that gap, and to the casual observer it can take on the appearance of JKD sparring, Wing Chun Chi Sao, or elements of what Mr. Parker created to support his tournament, "Freestyle Formulas" rolled at various times into one. The "Freestyle Formulas" were only part of the equation and Parker begrudgingly created them. He personally didn't believe in that type of sparring after his exposure to the Chinese Methodology.
They are specific technique applications designed for expedious results when an imminent attack is anticipated. When practiced as drills to enhance body mechanics and build hand eye coordination, they take on a rapid back and forth movement, with each participant being forced to effectively react to the external stimuli, or suffer reasonable training consequences. We wear special gloves, a boxing mouthguard, a big cup, and with drills, forearm protection.