Question

is there difference in using

<c:out value="${a}"/>

and just

${a}

in a JSP file?

Answer 1

Yes, JSTL’s out tag will transform certain characters to their XML escape sequences as stated in the documentation:

Attribute escapeXml: Determines whether characters <,>,&,'," in the resulting string should be converted to their corresponding character entity codes. Default value is true.

Note that if the goal is to produce cleaner markup then look at the escapeXml function in the http://java.sun.com/jsp/jstl/functions namespace as an alternative.