I applied to Northwestern early decision. I'm a little confused about your question... you can apply early as a regular decision applicant, or you can apply early as an early decision applicant. If you apply ED, you have an earlier deadline than those that apply regular decision and if accepted, you are bound to that one program and are unable to apply to other schools. However, if you are deferred to regular decision or rejected, you are free to apply to any school that you would like to.