A grant is funding typically given by a non-profit organization, usually for a specific project or because the recipient met certain criteria. A grant may be given for any purpose, not necessarily just for education.
Scholarships are specifically for students to pay for education. They usually have requirements for the student before and after they've been awarded the scholarship. Typical requirements include maintaining a specific GPA or taking a specific number of credit hours.
When you receive a grant for a project, you may be required to provide ongoing reports to the funding organization about your project. In some cases, grant and scholarship funds are released according to a schedule, and funds may be withheld if the reporting or minimum criteria are not met.
Neither grants nor scholarships require you to repay the funding organization. Only loans require repayment.
Scholarships and grants are not just based on financial need. They are sometimes awarded for specific majors, activities, abilities, affiliations or interests.