What is the difference between rt and el versions of the JSTL?

What is the difference between RT and EL versions of the JSTL?

That is, when coding a JSP in a JSP 2.0 or later environment开发者_StackOverflow社区, what are the important functional differences? Are there any?

The only clear explanation I've read is that EL is supported outside of tags and is a part of JSP 2.0 whereas RT is compatible with earlier JSP versions. Is that it?

When using JSP 2 or higher, there is no reason to use the RT version, which was provided as a stop-gap measure to allow pre-JSP 2 engines to use JSTL.