Final answer:
A formal inquiry includes a set purpose or goal, while an informal inquiry has no set procedure.
Step-by-step explanation:
A formal inquiry includes a set purpose or goal, while an informal inquiry has no set procedure. In a formal inquiry, there is a structured approach with specific objectives and guidelines, whereas an informal inquiry lacks formal structure and can be more flexible. For example, a formal inquiry could be a scientific study with a hypothesis and specific research methods, while an informal inquiry could be a casual conversation or discussion without a predetermined agenda or outcome.