What are the differences between those two in regards to UML diagrams?
Aggregation (and composition) are both special types of association that involves a kind of "part/whole" relationship... for example, if one class conceptually is made up of several pieces that are each represented by other classes.
i believe an association is similar to inheritance, and aggregation is when one class interacts with another like we talked about on the CRC cards in the collaboration section.
No, association is not similar to inheritance. Inheritance in UML is done by a generalization arrow.