The difference between a Service Level Agreement (SLA) and an Operional Level Agreement (OLA) is that:

A Service Level Agreement is a formal, legally binding contract between a service provider and a customer that specifies agreed service levels and the consequences of failing to meet them. An Operational Level Agreement, by contrast, is an internal agreement between teams within the same organization and is treated as a best-efforts commitment without the same legal enforceability.

While SLAs and OLAs do differ in what they define, this choice omits the critical legal binding nature of an SLA versus the best-efforts character of an OLA, which is the primary tested distinction.

Service Level Requirements are input documents capturing customer expectations, and Service Level Targets are measurable values that appear in both SLAs and OLAs - this choice conflates distinct ITIL Service Design concepts.

SLAs can be established with internal customers as well as external ones, so using external-versus-internal party as the sole differentiator is incomplete and misleading.