What is the difference between a 504 Plan and an IEP?

An IEP is used to plan specially designed instruction and related services necessary for a student to make progress in the general education curriculum. A 504 Plan outlines reasonable modifications needed by a student who has a documented disability. Students who receive 504 plans are not in need of specially designed instruction but rather need modifications that allow them equal access to school-wide curricular and co-curricular activities.