Are blocks in hand considered items?

[tahishae]

I am having difficulty understanding some differences between an item and a block. This is what I understand so far:

Inventory	Block	Item	Understanding
Stone	x		In placed position, it is a cube / block
Dandelion	x		In placed position, it takes up an entire cube/block area and nothing else can be placed on that coordinate
Iron Axe		x	It can only be in the player's hand; If the right click (or the set shortcut for placing blocks) is triggered, the axe is either used in a different function or dropped out of the player's hand

I am mostly confused about whether blocks are also considered items when it is not placed on a coordinate. For example, the block is in a chest, the block is in the player's hand, and the block is in a block with an entity (such as a cobblestone in a furnace). What exactly is considered a block and item?

[Laycee]

If the block, isn't placed, it is an item. Anything you can pick up and store in slots of your inventory or a container like a chest is an item.