Short answer. Both charge a person with an offence in writing, but they differ in who signs and files them. A complaint is a sworn statement subscribed by the offended party, a peace officer or an enforcing public officer; an information is subscribed by the prosecutor and filed with the court.
What the law says
A complaint is a sworn written statement charging a person with an offense, subscribed by the offended party, any peace officer, or other public officer charged with the enforcement of the law violated.
Rule 110, Section 3 — Complaint defined. Read the full provision →
What the law says
An information is an accusation in writing charging a person with an offense, subscribed by the prosecutor and filed with the court.
Rule 110, Section 4 — Information defined. Read the full provision →
The complaint
Rule 110, Section 3 defines it: A complaint is a sworn written statement charging a person with an offense, subscribed by the offended party, any peace officer, or other public officer charged with the enforcement of the law violated. Three features stand out. It must be sworn — the signatory takes an oath to it. It comes from outside the prosecution service: the victim, a police officer, or the public officer who enforces the particular law violated. And it is the ordinary starting point of a criminal case, the document by which a private citizen first puts an accusation on record.
The information
Section 4 defines its counterpart: An information is an accusation in writing charging a person with an offense, subscribed by the prosecutor and filed with the court. Notice what is absent: the definition does not require the information to be sworn, because the prosecutor signs it as a public officer acting in an official capacity. Notice also what is present: it is filed with the court — the information is the charging document that actually opens a criminal action before a judge. Where the complaint speaks with the voice of the offended party, the information speaks with the authority of the State.
The differences that matter
Set side by side, the definitions separate on three axes. Who subscribes: the offended party, a peace officer or an enforcing officer for a complaint; the prosecutor for an information. The oath: a complaint is a sworn written statement, while an information's definition says nothing of an oath. And destination: the information is by definition filed with the court. In the usual sequence the complaint is where an accusation begins, and the information is how it reaches the court — the aggrieved party complains, and the State, through its prosecutor, decides whether to carry that accusation into a criminal action.
Why the distinction matters to you
If you are an offended party, understand that signing the complaint does not make you the prosecutor: once an information is filed, the case is the State's to conduct. If you are the accused, the document charging you must fit its definition — an accusation in writing, subscribed by the proper officer — and defects in the charging document are among the first things defence counsel examines. Either way, identify which document you are holding: a sworn complaint bearing an offended party's signature and an information subscribed by a prosecutor are different instruments doing different work in the same case.