Specialized security provides increased security controls for roles with an elevated business impact (if compromised by an attacker or malicious insider).
Specialized roles typically include:
- Developers of business critical systems.

https://learn.microsoft.com/en-us/security/privileged-access-workstations/privileged-access-security-levels#enterprise
Enterprise security is suitable for all enterprise users and productivity scenarios. In the progression of the rapid modernization plan, enterprise also serves as the starting point for specialized and privileged access as they progressively build on the security controls in enterprise security.
Privileged security is the highest level of security designed for roles that could easily cause a major incident and potential material damage to the organization in the hands of an attacker or malicious insider. This level typically includes technical roles with administrative permissions on most or all enterprise systems (and sometimes includes a select few business critical roles)...