There are 3 types of HUDs in games. Permeant, Action and Pull-Up
Permeant HUDs are a part of a HUD that you can see at all times during the game for example Map, ammo and mana.
A Pull-Up HUD is a part of the HUD that is only seen when a button or somewhere on the screen is pressed. This could be an Inventory of the player of the exiting game HUD or when you purchase an ability in League of Legends .
A Action HUD is a HUD that is only seen when an event in the game occurs for example a red screen when you are close to death or when money is throw into the van in PayDay 2 a HUD pops up showing “You have bagged $300,000 artwork”.