The writing style in both of the plays are different. Thats what seperates the comedies from the tragidies. Shakespeare had done this on purpose because it was meant to reach a certain audience. Back in his day, comedies were put on for the commoners and the tragides, or the more serious plays, were meant for the higher class.
In Othello, the writing style is based on irony of all kinds. The language is more spohisticated and the characters are more elegant from their appearance to their speech. The situations are more catastrophic and the characters are more cunning.
In the Comedy of Errors, the writing style is more fun and animated. There is always something that goes wrong throughout the whole story. They express their feelings to the other characters but they do it indirectly so they never get to the source of the situation.

http://www.bookrags.com/studyguide-othello/style.html
http://www.shmoop.com/comedy-of-errors/writing-style.html

Argument: Shakespeare writes comedy plays in order to educate the reader.

Claim: The reason that Shakespeare creates the characters in his comedies to be somewhat uneducated is to teach the reader how not to behave. He influences the reader to feel emotion for the foolish characters that he creates.

Evidence: "...the showing of characters behaving as people ought to behave, of characters behaving evilly or foolishly and thereby warning us not to follow their examples, and of characters whom we are made to sympathise with, but who, nevertheless,behave in a foolish way."

http://search.ebscohost.com.lib.chandleraz.gov/login.aspx?direct=true&db=lfh&AN=48303388&site=lrc-live. This tells me about a couple biographies about Shakespeare so I can understand what envoked him into writing comedies and tragidies. What was he really like?