There are differences between the two.
Our opinions are the results of personal experiences, perspectives, and thoughts. They are valuable because they reflect something that could be universal. But it might also be true that our opinions are limited and might not serve others, let alone the impact of the whole. Sharing our opinions benefits the whole, but not all opinions should be treated as advocacy.
Because advocacy aims to influence decisions within political, economic, and social systems and institutions, one way to decide what we advocate is to find common ground where the solution is universal and for the betterment of the whole.
When a solution works for one situation but conflicts with the others, we might have focused on something that’s either a symptom of a more significant cause or too small.