Really both mean the same but the second sentence is not quite corect. You'd rather say i have a different opinion from yours.

Both are awkward, and the second is incorrect I have some opinions that are different from yours. I have some opinions that are different to yours. I have some different opinions to yours. I have some different opinions from those you hold. My opinions are different from yours. are all more natural

The intention of the two is the same, but the second is certainly not natural. The form would generally apply to a third person, not to the second person (i.e. not to the listener). Since it is plural, furthermore, it should be 'those', and not 'that'. I have some opinions different from those of Mr. X. My opinion is different from that of Mr. X

Yeap. Those ones are correct. You can say twice and the other person would undertand the same idea.

Yes, they mean the same thing, but it is more "natural" to say: "My opinions differ from that of yours," "I have some different ideas than you do," or "My opinions are different than yours."