fact and theory

 In theory oil is a non-renewable resource

in fact it will become uneconomic to extract before it runs out

in theory  animal species are renewable resources but it is possible that they become extinct and never capable of reproduction

A fact is an observable and verifiable event, while a theory is a well-substantiated explanation for a set of facts. In everyday language, "theory" can mean a guess, but in science, a theory is a powerful, evidence-based framework that explains phenomena and makes predictions. A fact is a single observation, while a theory is a comprehensive structure built from many facts.