This Wikipedia page says, "In contrast to collocation, co-occurrence assumes interdependency of the two terms". But I'm not really sure what that means by interdependency of the two terms. Can someone explain it more?
This is a really interesting question. I did some reading, and it looks like "co-occurrence" refers to when terms occur in the same document (corpus, paragraph, sentence). They do not necessarily need to be adjacent. For example, when the term "strong coffee" appears in a document, the term "espresso bean" probably also tends to occur in that document.
On the other hand, a "collocation" is two words that frequently appear together, in the adjacent sense. So, "strong coffee" is a collocation, because we see those terms occur next to each other more often than would be expected from pure chance. Hypothetically, the term "powerful coffee" is a synonym, but we very rarely see these two words occur next to each other.
The wikipedia article probably should be edited, to not make the two terms not seem so readily comparable. An example of how the terms should be used in distinct contexts comes from this paper:
"This statistical technique identifies the groupings of collocations that tend to co-occur frequently in texts" [emphasis added]
Here's some other possibly relevant papers that I came across: