All button components have type 2

for what the button says (max 80 characters)

a dev-defined unique string sent on click (max 100 characters). type 5 Link buttons can not have a custom_id

For different styles/colors of the buttons

Emoji object that includes fields of name, id, and animated supporting unicode and custom emojis.

optional url for link-style buttons that can navigate a user to the web. Only type 5 Link buttons can have a url

Whether or not this button is disabled