Globals are app-wide tags which can be used in your view layouts. In contrast to entity attributes, users can set the global value in the plugin settings page, thus applying to all entity records.
You can use WPAS tag functions for displaying date and time information in your view layouts. Some of these tag functions may accept additional parameter called a format string to determine how the date is going to be displayed.
A taxonomy is a way to group things together. It might contain only one attribute of interest to users. You can define hierarchical (terms with a parent term) or nonhierarchical (terms without a parent term) taxonomies.
Relationships are connections between entities. A relationship captures how entities are related to one another. For example, customers place orders, customers live at addresses, and line items are part of orders.