Light nodes do not store transactions and blocks, so the transactions collections is empty and the chain collection gets cleaned up periodically. This means that the rpc calls getBlockInfo and getTransactionInfo won't work. Other than that light nodes are the same as full nodes.
But I still have to make a few improvements as suggested after a review by eon / mancer. Here you will find a few more technical details @primersion/hive-engine-light-nodes