Litecoin is using largely the same consensus rules as Bitcoin with a few exceptions:
its blockchain derives from a distinct Genesis block
it targets a block interval of 2.5 minutes (10 minutes on Bitcoin)
halvings happen every 840,000 blocks (210,000 on Bitcoin)
block hashes are calculated with Scrypt instead of SHA-256d
Since the more costly Scrypt ...
Even though the software defining the Litecoin network is derived from Bitcoin's, Litecoin is a completely independent network with incompatible consensus rules.
Most notably Litecoin's Genesis block differs from Bitcoin's and therefore not a single block or transaction overlap between the networks.