What's the difference between validator nodes and full nodes?

Two types of nodes in the Libra network: Full nodes and Validator nodes. The Libra protocol can be configured to run either as a validator node or as a full node.

Validator nodes: Are run by members of the validator set (i.e., Libra Association Members)
Full nodes: Are run by anybody

Validator nodes: Validate transactions as part of the consensus process that is part of the operation of the Libra Blockchain
Full nodes: Validate transactions as a part of synchronizing to the Libra Blockchain from validators

Validator nodes: Are focused on writes — they accept transactions from clients and insert them into the Libra Blockchain
Full nodes: Are focused on reads — they can handle queries from clients and provide scale for the validators

Validator nodes: Provide signatures that authenticate the state of the Libra Blockchain
Full nodes: Rely on validator signatures to prove the correctness of their results to clients

Validator nodes: Are only required to have knowledge of the current state of the blockchain
Full nodes: Maintain historical information about the state of the blockchain