Type Purpose
Standard Select/Option Dropdown

User needs to pick one option from a list.

Dropdown Group

UI solution calls for multiple Dropdowns in the same area (ie. group of Dropdowns used as filters for the same list).

Advanced Dropdown

User needs to pick one option but there is a need within the UI to customize the option item (ie. want to pair an icon to an option or provide secondary content).

Advanced Dropdown - Multi Column

Allows for more than one selection. Data is categorized in multiple columns.

Action Button w/ Dropdown Menu

User has multiple actions or options available.