whats the difference between.....

Intersubjectivity (literally) refers to things that are common between the subjective relations of individual people to the world. That is, you and I might subjectively believe that a certain thing is beautiful, even though this is not officially "objective."

Objectivity refers to truths that are true regardless of the subjective position that analyzes them. For example, it might be argued that 1 + 1 = 2 is an objective fact.

The situation gets very tricky, though, in distinguishing between the two, because your interpretation depends very much on what criteria of truth you apply, etc. For example, is a statement that every agrees on "on their own" ("subjectively") actually objective? If noone disagrees, and everyone has the same view on the matter, it is hard to see how it is subjective. You could of course argue that someone could, "in principle," disagree, but the grounds on which it is "possible to disagree" are obviously varied.

On the opposite end, it is also possible that I define different rules for arithmetic, so 1 + 1 is not equal to 2. This sum is actually the result of a subjective assumption about the number system, and so should be called intersubjective based on convention.