In Criminal Procedure Code (CrPC) 1973, criminal cases are divided into summon cases and warrant cases. This categorisation of criminal cases has been done intentionally because the procedure of trial in the two cases is different as the seriousness of crime varies. The trial procedure for warrant cases is much more elaborate than in the summon cases. In order to understand it, the definition of each type has to be looked upon.
Summon case as defined in section 2(w) of CrPC, says that it is case relating to an offence, and not being a warrant case. While on the other hand, a warrant case is defined in section 2(x) of CrPC as a case relating to an offence punishable with death, imprisonment for life or imprisonment for a term exceeding two years. In simple terms, a case would be called a summon case if imprisonment is for less than two years and would be called a warrant case if the imprisonment exceeds two years. So, warrant case- being serious in nature and gravity of the offence being high, procedure of trial would, obviously, be more elaborate than the procedure of trial in summon case. In summon cases, summon shall be issued while in the cases of warrant cases, warrant shall be issued unless the magistrate thinks fit to issue summon. go to link 
Now the question is whether a summon case can be tried as a warrant case or a warrant case can be tried as a summon case? The answer to this question is given in the case of Kishori Lal v. Mahadeo [ 2 ]. The court held that it is possible that a summon case can be tried as a warrant case in the interest of justice. And in the same way a warrant case can be tried as summon case and can proceed with the procedure of summon case if the interest demands so. Procedure for the trial of summon case is provided by chapter XX of CrPC while procedure for trial of warrant cases is provided by chapter XIX of CrPC.
What will happen when the court opted for the procedure of a warrant case in summons case and procedure of summon case in a warrant case? In this regard, section 465 of CrPC is much relevant which says that if in the opinion of the court, there is a failure of justice then the court may rectify that irregularity in the interest of justice and the mistake or irregularity will be curable under the said section. But if a warrant case is tried as a summon case then there is more chance of vitiating of the trial and the interest of the parties can also be prejudiced.
Two types of procedures for trial are mentioned under CrPC. One is upon filing of police report or the case is instituted on other than the police report. In the case of warrant case, these two procedure can be followed according to the situation but in the case of summon case only one procedure will be followed irrespective of who is filing the report. Now for the sake of simplicity let’s try to understand it in a tabular form.
|Basis of Points||Summon Case||Warrant Case|
|follow link Meaning||Summon case is a case for which punishment is less than two years.||Warrant case is a case for which punishment is more than two years.|
|click here Procedure||Only one procedure is prescribed under CrPC.||Two procedures are given. One is on institution of the case on police report and second is on institution of the case other than the police report.|
|Charges||Framing of charges is not necessary as the gravity of offence is lesser.||Framing of charges is mandatory as warrant case is a very serious offence whose gravity is much higher than the summon cases.|
|Conversion||A summon case can be tried as warrant case in the interest of justice.||Conversion of warrant case into summon case is very rare but it can be done by the court in the interest of justice.|
|Withdrawal of complaint||In summon case if complainant withdraws the complaint then the accused will be released.||In warrant case if complainant withdraws the complaint then accused shall not be released.|
In short, summon cases are much faster in resolving than warrant cases because of a very simple reason- gravity of offence is much higher in summon cases than in warrant cases.
 Section 204 of CrPC.
 1993 CrLJ 1173 (AII).