An opinion is an unsupported claim; an argument is a supported claim.
The expression of personal opinion is one of the most common form of verbal exchange, and since reasons for our opinions are often not requested, we are unaccustomed to defending them and are even lulled into thinking that reasons are not required. “Everyone is entitled to his or her opinion,” it is often said. This is true, but the question here is not whether one has the right to express an opinion; it is a question of which opinion deserves out acceptance. If an opinion is not accompanied by reason to support it, it is not possible to determine whether it merits our acceptance.
Most of us enjoy exchanging out opinion with others, but rarely do our opinions change unless arguments for another position are presented. And there is reason to believe that some of our opinions need to change, because some of them conflict with each other and therefore cannot all be true. Since some of our opinions also conflict with the opinions of others, we know that some of us are now holding false opinions; for if there are two opposing opinions or different opinions about some matter, at least one of them is false. But which is it? That question can be answered only by evaluating the quality of the argument presented on behalf of each view.
Attacking Faulty Reasoning: A Practical Guide to Fallacy-free Arguments
By T. Edward Damer
Emphasis of [underline,bold] is mine!