EA, Early Action

 It is best that you have a first choice school in mind first , the application policy varies from school to school. Early Action and regular application have the same standard. The difference is that you can apply early and know the result early.    If you are accepted in the Early Action cycle, you do not have to decide if you want to enroll or not.  You can still apply to other schools in the regular application cycle.   If have a better offer ,you can tell the EA school that you will not be attending.  

You must realize that some colleges have restrictive early action plans, in this case, you can only apply for one college in the early admission cycle.  

Here is a FAQ from YALE. https://admissions.yale.edu/faq/single-choice-early-action