Two entirely different things.

JNDI is naming service, where you can access a service in a container with given name. Once you have the access, you can utilize that service.

Teiid is a Data Virtulaization system, where you can integrate data from multiple heterogeneous sources. Say for example you have some data in a file and some data in Oracle database, you want to integrate both the sources and provide single view of the data, then Teiid is tool you want to use. There is leanty of meterial you can read on http://teiid.org and lots of quick start examples if you are interested in learning.

HTH

Ramesh..