A research grant proposal is a comprehensive document that outlines your project or program, explains its significance, and requests funding. It typically includes sections such as an executive summary, introduction, project description, budget, and evaluation plan. On the other hand, a grant letter is a shorter document that serves as an initial contact with a potential funder. It is typically a letter of inquiry or a letter of intent that provides a brief overview of your project, highlights its relevance, and expresses your interest in seeking funding. A grant letter is often used to gauge the funder's interest before submitting a full grant proposal.