The key point is thus the following
Common law is a system of judicial supremacy; canon law is a system of legislative supremacy
This answers the following question: who has the authority to interpret what is the meaning of a given law?
In the Common Law this power of interpreting the meaning of the written law resides in the courts. As a consequence a) the legislator, when writing the law, tries to put as much details as possible, to prevent and interpretation contrary to its goals; and b) the lawyers, when preparing for a case, would consult a vast literature of pervious court ruling in that matter.
In the Cannon Law the power of interpreting the meaning of the written law resides with the legislative power. This is stated as follows in the 1983 CIC 16 § 1 “The legislator authentically interprets laws as does the one to whom the same legislator has entrusted the power of authentically interpreting.” And the proof that the courts have not the power to generically interpret the law is also states in the 1983 CIC 16 § 3 as follows: “An interpretation [of law] in the form of a judicial sentence or of an administrative act in a particular matter, however, does not have the force of law and only binds the persons whom and affects the matters for which it was given.” As a consequence of the supremacy of the legislator in interpreting matters of law, the cannon law articles tend to be shorter than the common law as they don't seek to deal extensively with all imaginable cases, and the few cases that may not be clear can be left to be decided by the ordinary Bishop or other authority. Another consequence of the supremacy of the legislative power is that cannon lawyers, when dealing with a disputable issue of which they want to assess the outcome, they turn on to cannon law commentaries, and more recently also to the study of development of the cannons. For cannon lawyers therefore Cannon Law commentaries and the study of its development play a similar role than the books of court rulings plays for a common law lawyer.