Erik Menendez owned his past by acknowledging he was a "spoiled brat" growing up, but things have radically changed.

Erik and Lyle Menendez were on TMZ's "2 Angry Men" podcast with Mark Geragos and Harvey Levin, and Harvey was blunt ... telling Erik when he covered their trial many years ago, his impression -- which was shared by many others -- was that they were spoiled brats.

Erik was clear ... guilty as charged, saying back then he thought he could mask his insecurities with expensive clothes and fancy cars. He went on to say measuring success by the stuff he acquired was ridiculous.

But Erik wasn't done, referencing his values back then by saying ... "I'm so ashamed and embarrassed." He says he now likes himself and his goal is to become a truly good person.

When you listen to the podcast, they make a case they are radically different from the 2 young defendants on trial for murdering their parents.

Erik and Lyle also talk about how they were brutalized behind bars early on in their prison stints ... and that includes Lyle suffering a broken jaw in a prison attack.