When you say “your own opinion” it means the opinion specifically belongs to the other person (for example: it is what the person has thought about alone, not because he has heard it on TV or read about it in the papers etc) “Your opinion” is not necessarily like that. For example: if you live in an apartment you say “It’s my apartment.” Then your friend talks about how beautiful and luxurious your apartment is and you say “It’s not my own apartment. I have rented it.” In the second case you are laying emphasis on the fact that “the apartment is not your property.”

Thank you Weronica. Is it like "Your personal opinion"? So there is a little difference between the two sentences.

Hello Franco, these two statements have the same meaning but the word 'own' higlights that this particular opinion is utterly your INDIVIDUAL, PERSONAL one.