You can use the definition of an HPA from the MPA Guide https://mpa-guide.protectedplanet.net/:
Fully Protected Area: No impact from extractive or destructive activities is allowed and all abatable impacts are minimized. Non-extractive activities may include recreational, traditional, cultural, or spiritual activities. Examples include minimal impact snorkeling, swimming and SCUBA, tidepooling, cultural/ceremonial gatherings, education, knowledge transmission, and motorized or non-motorized vessels associated with the previously mentioned activities.
Highly Protected Area: Only light extractive activities are allowed that have low impact, and all other abatable impacts are minimized. If any anchoring is allowed, it is small scale and for a short duration with a low impact. If any infrastructure is allowed, it is small scale with low impact. Any aquaculture must be low impact, small scale, low density, and unfed. If fishing occurs, it is infrequent and only five or fewer gear types are used that are highly selective and low-impact. Any non-extractive activities are regulated and restricted and of low impact, low density, and small scale.