Difference between a "jta-datasource" and a " resource-local " datasource?

The terms "jta-datasource" and "resource-local datasource" are a little vague to me. I'm putting down what I am understanding ( or assuming ) and I'd like you to say where I'm right / wrong.

• The same database can be referred to as a jta-datasource or as a resource local datasource
• If mentioned as jta-datasource, then the beans / other classes can use JTA. Hence, UserTransaction interface
• Cannot use CMT / BMT if the datasource is resource local
• If mentioned as resource local datasource, transactions are not JTA aware. Code can use EntityTransaction interface but not UserTransaction interface

Thanks!