WAS 502 vs WAS 502 Express

WAS Express info from the IBM website:
The Express Application Server is supported on Windows NT, Windows 2000,
Windows 2003, Windows XP, Red Hat, SuSe, United Linux, AIX(r), Solaris,
HP-UX, and OS/400

WebSphere Application Server - Express supports Cloudscape(tm), DB2, SQL,
SQL Server, Informix(r), Sybase, MySLQ, InstantDB, and Oracle.

Functions included, but are not limited to:

JDK 1.3.1 support
JSP 1.2 including Custom Tag Libraries
Java Servlets 2.3
Web Services (SOAP 2.2, WSDL, and UDDI client)
Java Security model including APIs and J2EE authentication and authorization
XML tools, including Xerces and Xalan
JDBC
Connection pooling
JNDI
Struts

Application Server - Express does not include an external HTTP server
because it includes an internal HTTP server.
It does not include functions that link multiple servers together like
failover and network deployment.
Complex functions like EJBs, JMS, and JCA, are not included.