guarantee VS warrant

guarantee

 

2 a firm promise that you will do something or that something will happen  

synonym assurance 

to give a guarantee of good behavior 

He gave me a guarantee that it would never happen again. 

They are demanding certain guarantees before they sign the treaty.

warrant

 [countable] warrant (for something) a document that gives you the right to receive money, services, etc. 

the issue of warrants for equity shares

 [countable] a legal document that is signed by a judge and gives the police authority to do something 

an arrest warrant warrant for something 

They issued a warrant for her arrest.  

warrant to do something 

They had a warrant to search the house

MORE INFO :  http://oaadonline.oxfordlearnersdictionaries.com/dictionary/WARRANT