IMO the multi-level system is a result of near revolt that started in the late 70's early 80's. There was only one compulsory (class III) level, and two compulsory/optional levels (class II & classI) where the athletes woulkd perform compulsory routines as well as optional routines, and then the elite program. Many coaches felt the "one size fits all" class III level was established with routines too easy to challenge kids that were poised for optionals, while others complained class III was too hard for entry level team gymnasts. Many coaches with accelerated programs would try to "alter" some of the key developmental elements to compliment a child's training toward the Class II Level. The governing body responded by pulling sanctions for meets where altered skills had been performed as a means of controlling the situation, but IMO found they were fighting an up hill battle.
As these struggles were taking place at the Class III level, a collection of coaches complained that there first and second year class II's were being dominated by third and even fourth year Class II's at competitions. Many of these coaches tried to compensate by abandoning the compusory routines for their first year Class II's, as well as their "weaker" second year Class II's, which then made these participants ineligible for state and regional championships.....If you guessed it resulted in a "black market" state championship for the "optional only" Class II gymnasts, you deserve the "back seat" coach of the year award. Mayhem reigned supreme for about four years until U.S.G.F. president (ask dunno) Mike Jacki personally called coaches in every region to ask for solutions and suggestions on how to reshape the age group program.
This gave rise to a system that included a novice (class IV) level, altered the Class III level to include the option a competing compulsory AND optional routines with reduced requirements and restrictions with repect to difficulty, and validated the Class II optional only concept. So let's all give that man a robust ovation wherever (help me dunno) he is, as it was his willingness to accept change that allowed us to evolve into the current multi-level program. Since the current program evolved from the three level system to allow a variety of "sizes", I would answer you by saying each level is a practical and incremental step between the level "below" it and the level "above" it. In the case of level 7 compared to eight?......the level 7 requirements to reach a score of 10.00 are fewer, with "inappropriate skills" that don't receive credit as well as restricted skill that if included in a performance will result in a 00.00, while the 10.00 requirements at level 8 are more various, more difficult, and fewer skills are restricted. So if I have satisfied you with this history lesson, I'd like to go back to re-living another glorious moment in history I've witnessed in my life time. The invention of rocks!!!!
P.S......I just noticed my "post to like ratio" has dropped below 3 to 1, so how 'bout a little love?