Difference Between QUOTED_IDENTIFIER ON and QUOTED_IDENTIFIER OFF In SQL Server

When SET QUOTED_IDENTIFIER is ON, identifiers can be delimited by double quotation marks. It other words when QUOTED_IDENTIFIER is set to ON then string inside treated as a identifier not as a literal.
 
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When SET QUOTED_IDENTIFIER is Off literals can be delimited by double quotation marks. It other words when QUOTED_IDENTIFIER is set to ON then string inside treated as a literal not as a literal.
 
Example