Regular Decision: Submit application by a specified date and receive a decision in a stated period of time. These are often January deadlines. California state schools and UC schools have deadlines of November 30th.
Rolling Admission: As soon as the application is available, student may apply and will get a decision shortly after that. Applications are reviewed as they are submitted and decisions are given throughout the admission cycle.
Early Action: Deadlines are usually late October and early November, some December. Students apply early and receive a decision well in advance of the regular decision response date.