Section 504 of the Rehabilitation Act of 1973 is a federal law which protects students from discrimination based on disability. A 504 plan is developed by a student's team (parent, teacher, counselor, school psychologist) to ensure that a studetn receives accommodations that will ensure their academic success and access to the general education learning curriculum and environment. A 504 plan does not alter the general education curriculum to create specially designed instruction. A 504 plan consists of accommodations provided in the general education setting. (By contrast, special education provides an Individual Education Plan to provide specially designed instruction, which may alter the general education curriculum.)
Which is better for your student? That would depend on the barriers the disability presents.
Andy Wheeler oversees 504 plans for the district, and the counselor in each school monitors 504 plans in each school.
If you have concerns about your student's progress, please make an appointment to meet with your child's teacher and/or the school counselor or social worker. They can help decide how to move forward.
For more information on 504 plans, one place to visit is OSPI's page on 504s.