"Our cloud's a little bit different. It's both platform as a service and applications as a service," he said during a keynote address at the OpenWorld conference in San Francisco, which was webcast. "The key part is that our cloud is based on industry standards and supports full interoperability with other clouds. Just because you go to the cloud doesn't mean you forget everything about information technology from the past 20 years."

In contrast, Salesforce.com's Force.com platform is the "roach motel" of cloud services, amounting to "the ultimate vendor lock-in" due to its use of custom programming languages like APEX. In contrast, the Oracle Public Cloud uses Java, SQL, XML and other standards, Ellison said.

"You can check in but you can't check out" of Salesforce.com, Ellison said to laughter from the OpenWorld crowd. "It's like an airplane, you fly into the cloud and you never get out. It's not a good thing."

Salesforce.com may have bought Heroku, a cloud application platform that supports Java, but customers shouldn't be fooled, Ellison claimed.

"They say, 'Oh, we just bought Heroku. It runs Java.' [But] it's sort of like a Salesforce.com version of Java that only runs in Heroku. Don't try to move that [Java Enterprise Edition] application to the Salesforce.com cloud. It won't run. If you build something in Heroku you can't move it. It's a derivative of Java."