The block height is just the number of blocks connected together in the block chain. Height 0 for example refers to the very first block, called the “genesis block.”
A sequence number of a block in a blockchain. Height 0 refers to the genesis block. Several blocks may share the same height, (see Orphan ), but only one of them belongs to the main chain.
Malone, J.A (2015). Glossary of Bitcoin Terms and Definitions. United States: Lulu Press, Inc