Being waitlisted means the college has finished reviewing your file and decided to put you on a waiting list for admission. If waitlisted, I would recommend writing a letter of continued interest. 

 (see templates below)

Generally, you can assume your odds are better if you've been deferred rather than waitlisted.  

A deferral is neither a rejection nor an acceptance; it's a "maybe." Deferred admissions mean that an institution has not completed reviewing an application file and will decide on admission status later. 

 Ultimately the institution needs more information (most will want to review the mid-year transcript before they make the final decision) to see if you're a good fit.