Explanation
Affiliation and Attribute are two key objects used with EDA. Affiliation is an object that represents a relationship between a Contact and an Account or another Contact. Affiliation can be used to track various types of relationships, such as student, faculty, staff, alumni, donor, or advisor. Attribute is an object that stores additional information about a Contact or an Applicant that is not captured by other EDA objects.
Attribute can be used to track various types of information, such as test scores, languages, hobbies, certifications, and documents. Opportunity and Account are not key objects specific to EDA, but rather standard Salesforce objects. References:
https://powerofus.force.com/s/article/EDA-Affiliations
https://powerofus.force.com/s/article/EDA-Attributes
https://powerofus.force.com/s/article/EDA-Data-Dictionary