While full nodes form the backbone of the Bitcoin network light nodes provides for ease of use.
A light Node does not download the complete blockchain. Instead, it downloads the block headers only to validate the authenticity of the transactions. Because of this reason light nodes are easy to maintain and run. Lightweight nodes use a method called Simрlifiеd рауmеnt vеrifiсаtiоn (SPV) to verify transactions.
Lightweight nodes are served by full nodes to connect to the Bitcoin network. They are effectively dependent on the full nodes to function.
Lightweight node wallets have a number of downsides that users should be aware of. These downsides can all be avoided by configuring a lightweight node wallet to connect only to your own full node.
Lightweight wallets do not validate the rules of bitcoin. If somebody pays a lightweight wallet user with fake or invalid bitcoins, then wallet will happily accept them and the user will be left out of pocket. See Also: Full node#Economic_strength
Lightweight wallets typically send addresses to a trusted third party and receive wallet balance and history. This allows the trusted third party to spy on all the users past and future transactions. Full node wallets avoid this serious privacy leak by downloading the entire blockchain and scanning it locally.
Lightweight node wallets skip several security steps which can leave the user vulnerable. An example of a situation where this was important was the 4th July 2015 accidental chain fork where updated full node wallets were unaffected while lightweight node wallets were in danger.