Node

A node refers the a computer running an the blockchain client.

Validator Node

These nodes are responsible for producing blocks on the blockchain.

In general, they only keep the current state of the blockchain, that is required for block production and does not keep previous (unnecessary) blocks. This significantly eases the storage requirement for the node (from multiple TBs to just a few GBs).

Archive Node

Contrary to validator nodes, archive nodes keep every block on their storage. This is useful for archival purposes and if the user wants to run an Indexer.

Bootnode

These nodes are a special subtype of archive nodes. When a new node connects to the network, it automatically connects to one of the bootnodes to download the required blocks. These are typically hosted by trusted individuals / organizations.