In 2017, part of the community proposed increasing the block size to allow a greater number of transactions per second. This proposal clashed with those who defended keeping small blocks and scaling through off-chain solutions, such as Lightning Network.
The lack of consensus led to a hard fork:
The original chain retained the name Bitcoin (BTC).
The new version adopted the name Bitcoin Cash (BCH), with larger blocks and a more transactional orientation.
Both share the same history up to block 478559, but their approaches are substantially different.
