The Criminal Code creates two categories of offences: summary conviction offences and indictable offences.
The trial of a summary conviction offence is before a different court and follows a different procedure from that of an indictable offence.  An appeal against the decision at trial goes to a different court of appeal.
Since indictable offences are more serious, a prosecution by indictment triggers additional procedural safeguards [FN1] and a conviction attracts more severe penalties.  Indictable offences also confront the accused with greater expense and delay, and carry greater stigma.

Hybrid offences
Some offences may be prosecuted either summarily or by indictment, at the Crown’s discretion.  These offences are commonly known as hybrid offences (or dual procedure offences).  Hybrid offences do not comprise a third category of offences. 

In hybrid offences, the same essential elements must be proven whether the Crown elects to proceed by way of indictment or by summary conviction.

In virtue of s. 34 of the federal Interpretation Act, hybrid offences are deemed at law to be indictable unless and until the Crown has elected to proceed summarily.  
R. v. Dudley, 2009 SCC 58, [2009] 3 S.C.R. 570, at para. 64 (in dissent, but not on this proposition);
See Interpretation Act, R.S.C., 1985, c. I-21, section 34(1)(a).

Crown Election
The Crown is entrusted with making the necessary determination whether to proceed summarily or by indictment, different means of prosecuting the offence. 
The Crown derives its power to proceed by indictment or summarily by common law, not statute.
An indication by the Crown on the Charge Screening Form as to how it will elect (summarily or by indictment) is not the Crown’s election. 
            See Stuart O’Connell Law Blog, The Charge Screening Form,
Crown election can occur more than one way:  

1.       Crown Expressly Elects

The Crown expressly elects to proceed summarily or by indictment; 

The Court of Appeal for Ontario has held Crown elections should be made expressly and recorded on the information: R. v. Mitchell, 1997 CanLII 6321 (ON CA).  However, this is not always the case.

2.   Crown Presumed to Elect Summarily

Where the trial has proceeded before a summary conviction court without an express election by the Crown, it will be presumed that the Crown has elected to proceed summarily.
R. v. Dudley, 2009 SCC 58, [2009] 3 S.C.R. 570, at para. 3

3. Crown Inferred to have Elected     

For instance, where the Crown has not elected, but the accused is put to his/her election as to mode of trial, it may be inferred that Crown has elected to proceed by indictment.

            R. v. Bee (1975), 28 C.C.C. (2d) 60 (BC CA);

R. v. Dudley, 2009 SCC 58, [2009] 3 S.C.R. 570, at para. 20: “the Crown will be deemed to have elected to proceed by indictment where the accused has been put to the election as to mode of trial required,”

The Exercise of the Crown’s Discretion

The court does not superintend prosecutors in the exercising of core areas of discretion
The Crown’s election is protected by a strong presumption of regularity and the offence is deemed to have been correctly characterized. The exercise of the Crown’s discretion is subject to judicial review only for improper or arbitrary motives. 
R. v. Balderstone (1983), 1983 CanLII 2803 (MB CA); 
R. v. Beare (1988), 1988 CanLII 126 (SCC);
See also R. v. Kelly, 1998 CanLII 7145 (ON CA).

Thus, in most cases getting the Crown to re-elect or to change its intention as to how it will exercise its discretion is a matter of advocacy.