Difference between apache and tomcat

Apache is the name of the foundation that writes open-source software,Apache HTTPD is a web server generally people call by the name Apache,

basically it is used for running static content , but there are so many add-on modules for servicing dynamic content for PHP,Perl,Ruby etc.,

Tomcat is primarily a Servlet/JSP container. It’s written in Java. It can serve static content also, but its main purpose is to host servlets and JSPs. Although it’s possible to get Tomcat to run Perl scripts and the like, you wouldn’t use Tomcat unless most of your content was Java.
It’s actually possible to use both Apache and Tomcat together, so that Apache serves the static content, and Tomcat the Servlets and JSPs. Depending on various factors, this may or may not be a good idea.