PageA page is used for displaying parts of the application to the user. 

Container A container is used to create groups of display elements that can be reused. 

ButtonA buttons is used so users can trigger an Event from a Page. 

  Field

ConversationA conversation is used to create a Q&A based interaction meant for guiding the user towards an answer of solution.

  Image

 Text itemA text items is used for displaying text in a document, or on a page.

Content itemA content item is used to create structure in text items and other content items.

AssetAn asset is used for displaying justifications on a page.  Asset