Medical complaint vs negligence claim: are they the same thing?

No. A complaint to a practitioner, health service or regulator is different from a civil claim for compensation. A complaint can focus on explanation, safety, records or service improvement, while a negligence claim requires proof of legal duty, breach, causation and loss under the applicable law. Keep the medical chronology and records organised before choosing the route. Guide: https://getinstantlaw.com/medical-negligence