Can someone give me a non-marketing explanation of DB2 Connect?

Ok so first a story, because maybe that's the wrong question. IBMs website
makes DB2/connect sounds like an ODBC or JDBC driver. That's not entirely
true from what I can surmise.

I installed DB2 Express-C on my windows laptop. I can talk to it with
SQLWorkbenchJ the same as my clients IBM i's (but with a different JDBC
jar. Everything is hunky dory. The install created an ODBC driver for me.

In PHP I used db2_connect() to talk to the windows local db2 instance from
windows with a connection string
"DATABASE=sample;HOSTNAME=localhost;UID=zippy;PWD=****". It worked. Process
monitor confirmed it was actually making a TCP connection, not named pipes
and not some shared memory connection like Microsoft SQL Server allows for
localhost connections. However, if I set the hostname to that of an IBM i
that I can connect via SQLWorkbench with jtopen, it doesn't even try to
make the TCP connection. I just get the following error:

Error connecting to DB2. 08001 [IBM][CLI Driver] CLI0199E Invalid
connection string attribute. SQLSTATE=08001 SQLCODE=-99999

So, is the ODBC driver not letting me connect because its checking some
license entitlement?

Justin