Yep.

The two do completely different things.  RowSet lives at the database
level, and gives you more flexibility to interact with specific query
results.  All the time, though, it works in rows and colums of a single
tabular data source.  Hibernate and JDO allow you to work with objects
and their relationships, and can store those at a higher level, defining
mappings from your OO data model to the underlying relational data
source.

There are several types of applications people may write.  You appear to
be working primarily with a database application, the essence of which
is to be a front-end over straight-forward data retrieval and storage.  
Most of your code would then be GUI and simple data access code.  In
those kinds of applications, it often makes sense to deal with the
database as a database, for example using JDBC (and RowSet is basically
an extension of JDBC).

For other applications, the core of the application is in processing
logic, and the use of a database is fairly incidental; in those cases,
it's best to have a more natural data model to work with than rows and
columns, and there are generally lots of interactions to manage between
relations of the database.  It would be a real pain to use a tabular
model of your data, such as RowSet, in applications like this; so JDO
and Hibernate (and several other alternatives as well) help allow such a
developer to use an OO model of data for calculation, and then take care
of the database transparently.