Bitcoin Cash (BCH) and Bitcoin (BTC) share a common origin, both stemming from the original Bitcoin blockchain. However, they differ primarily in their approach to scalability and transaction processing. The main distinction lies in the block size limit and the subsequent impact on transaction speed and fees.

Bitcoin Cash emerged in 2017 as a result of a hard fork from the Bitcoin blockchain. The key motivation behind its creation was to address the scalability issues faced by Bitcoin. While Bitcoin retained its 1 MB block size limit, Bitcoin Cash increased its block size to 8 MB, later further expanding to 32 MB. This larger block size allows Bitcoin Cash to accommodate more transactions per block, resulting in faster confirmation times and lower transaction fees compared to Bitcoin.

The differing block sizes also affect the two cryptocurrencies' approaches to on-chain scalability. Bitcoin Cash aims to process more transactions directly on the blockchain, emphasizing its use as a medium of exchange. In contrast, Bitcoin, with its smaller block size, leans towards off-chain solutions like the Lightning Network to enhance scalability while prioritizing its role as a store of value. Ultimately, these differences in scalability approaches shape the user experience and use cases for Bitcoin Cash and Bitcoin.