Start with what you already have
A complete design, a physical sample and an early market idea require different development work. Make an inventory of drawings, fit references, materials, artwork and specifications before asking for a quote. This exposes gaps that can otherwise emerge late in sampling.
When an OEM brief is useful
An OEM discussion usually starts from your design or specification. The review still needs to establish manufacturability, available materials, component compatibility and any open tolerances. A finished drawing does not automatically answer these production questions.
When an ODM brief is useful
An ODM discussion starts with more decisions open: intended wearer, product direction, construction or component choices. Define who develops each element and who approves it. Record permitted use, ownership and any tooling arrangements before work begins.
Compare the full scope
Compare development work, sample rounds, tooling, testing and production assumptions separately. Ask both parties to identify what is included, what requires a separate charge and what must be approved before the next stage.