There are ONLY 3 levels of Security Clearance
The ONLY levels of Security Clearance that exist are Confidential, Secret, and Top Secret. Anything else is either an approval or determination that does NOT involve classified information, such as a "Trustworthiness" determination or "Public Trust," or it is an access, which does deal with classified information, such as Sensitive Compartmented Information.
Accesses do exactly what the name implies. They give access to specialized programs and particularly sensitive classified information that is segmented unto itself. In order to be granted access to this kind of sensitive information, the person must first possess the underlying (usually called "collateral") clearance, normally at the Top Secret level. This is way someone will say they have "TS/SCI" clearance. What they really have, and what they really mean, is that they have a Top Secret clearance and also an SCI access.