Taking a quick read through the Tie::DBI pod, it looks like it doesn't support any of the relationships that Class::DBI does such has has_a and has_many. Also, it seems like CDBI's search() method is better than TDBI's select_where() method, and also CDBI has support for custom queries via set_sql but w/TDBI you just jet the dbh() to do it all yourself. TDBI docs also warn of performance concerns (but as for a direct TDBI-CDBI benchmark, i can't say). Another significant difference is that TDBI ties you to a hash, while CDBI provides objects to work with and all the obvious benefits that come with it (can't mispell hash keys, accessors/mutators, inheritance, custom methods, etc). Also note that CDBI has further support for specific databases in the Class::DBI::* modules (Class::DBI::Pg, Class::DBI::MSSQL, Class::DBI::mysql, etc), as well as Plugins. Class::DBI will also be far more supported by the mailing list and the wiki.

To summarize, I would say that TDBI is a lot more limited, and only consider it if your needs are very limited (just a couple/few unrelated tables), and even then I personally would still use CDBI.

Update: Summary bulletin points of things CDBI has that TDBI doesn't:

• relationships (has_a and has_many)
• search() better than select_where()
• custom queries (set_sql)
• better performance??
• provides an object, not just a hash
• db-specific support in the Class::DBI::* modules
• Plugins
• Support via active mailing list and wiki