The supply limit of Bitcoin and Ethereum represents a fundamental difference between the two cryptocurrencies. Bitcoin has a fixed supply limit of 21 million coins, which is hard-coded into its protocol. This finite cap is central to Bitcoin's value proposition, often likened to digital gold. The scarcity created by this limit contributes to Bitcoin's perception as a store of value, driving demand as it becomes progressively harder to mine new coins due to the halving events every four years, which reduce the reward for mining new blocks by half.

In contrast, Ethereum does not have a fixed supply limit. Initially, Ethereum's supply model was inflationary, with a substantial number of new ETH created each year to reward miners. However, with the transition to Ethereum 2.0 and the shift from proof-of-work (PoW) to proof-of-stake (PoS), Ethereum's issuance rate has significantly decreased. Additionally, the implementation of EIP-1559 introduced a mechanism to burn a portion of transaction fees, reducing the overall supply growth and sometimes even making ETH deflationary during periods of high network activity.

This fundamental difference affects how investors perceive each cryptocurrency. Bitcoin's fixed supply suggests a predictable scarcity, appealing to those looking for a hedge against inflation. Ethereum's evolving supply model aims to balance utility and value through dynamic issuance and burning, catering to both developers and investors in its ecosystem.