SAFE
Free from danger, harm, or risk in the moment. You are not likely to get hurt right now. (No immediate danger)
The children are safe inside the house.
She said that all the hostages were safe.
SECURE
Protected in a stronger, more permanent way; safe because of systems, controls, or protection. Long-term safety that cannot be easily harmed.
The building is secure with CCTV cameras and guards.
He managed to escape from the country's most secure prison.