An estimate provides a rough approximation of the cost of a project. It is based on limited information and focuses primarily on the budget. A proposal is a detailed document that outlines the specifics of a project, including timelines, deliverables, and costings. It considers the broader context of the project and aligns with the client's requirements. An estimate is usually a precursor to a proposal and may be provided free of charge, while proposals are usually more comprehensive and require more time and investment to prepare.