Technically, IEPs always involve services, but it is true that those services do not have to be in a pull-out setting. The key difference between 504s and IEPs is the presence/absence of specialized instruction, which entails changes in at least one of curriculum standards, performance criteria, or instructional methodology.
Depending on the nature of the need and the corresponding specialized instruction, some are more appropriately serviced in the inclusive general education setting, with special education support in the regular classroom, others require pull-out, and some are actually best implemented through consultation by specialists with general educators, providing them with additional strategies for supporting the student (e.g., tips on modifying tests, providing alternate assignments, targeting certain learning standards over others, reinforcing use of AT skills).
