you are likely to find Theater in/at/on Downtown. you are likely to find Program in/at/on Theater. Application is a type of Program. Application is related to Apple. 
Vary is related to Difference. Differ is derived from Difference. 
Downtown <--AtLocation-- Theater <--AtLocation-- Program <--IsA-- Application <--RelatedTo--> Apple 
Vary <--RelatedTo--> Difference <--DerivedFrom-- Differ 