Bitcoin and Ethereum get lumped together as "crypto". That's like lumping gold and the internet together as "stuff people use".
They're built for different jobs, run on different rules and behave differently in your portfolio. Here's the difference in five minutes.
The short version
- Bitcoin is digital money with a fixed supply. Only 21 million will ever exist.
- Ethereum is a platform for running programs called smart contracts. Ether (ETH) is the fuel that pays for them.
- Bitcoin's supply is capped. Ethereum's isn't, but some ETH is burned with every transaction, which can offset new issuance.
- Ethereum switched to proof of stake in 2022, cutting its energy use by about 99.95%.
- In markets, ETH has been the bumpier ride: it had nearly twice as many 5%+ days as Bitcoin over the past year.
Bitcoin: digital money, hard cap
Bitcoin was designed to be money that no government or company controls. Its defining rule: only 21 million bitcoins will ever be created. New issuance halves over time until it stops completely (bitcoin.org).
That fixed supply is the whole pitch. It's why people call it "digital gold": something scarce that can't be printed.
Ethereum: a world computer
Ethereum is a decentralised network and software platform that runs open-source programs called smart contracts. Ether (ETH) pays the fees to run them, and is staked by the validators who secure the network (ethereum.org).
Those smart contracts power most of what people mean by "crypto apps": stablecoins, decentralised exchanges, lending and NFTs. The Ethereum Foundation describes the goal as a "world computer" that anyone can use without permission (Ethereum Foundation).
Supply: capped vs flexible
This is the biggest difference most people miss.
- Bitcoin: a fixed maximum of 21 million.
- Ethereum: no fixed supply cap. New ETH is issued to stakers, roughly 1,700 ETH a day, but part of every transaction fee is burned and destroyed. On busy days, more can be burned than issued, so supply can shrink (ethereum.org, ethereum.org).
So Bitcoin's scarcity is set in stone. Ethereum's depends on how much the network is used.
How they're secured
Bitcoin uses proof of work: miners spend electricity to secure the network.
Ethereum switched to proof of stake in "The Merge" on 15 September 2022. Validators lock up ETH instead of burning electricity, and Ethereum's energy use fell by an estimated 99.95% (ethereum.org).
How they behave in a portfolio
Over the 365 days to 14 November 2026, Bitcoin's typical daily move was 1.16% and Ether's was 1.38%. Ether had 34 days of 5%+ moves against Bitcoin's 18 (MYEX volatility guide). In this month's sell-off, Bitcoin fell 15% in a week and Ether 21% (MYEX weekly note).
That fits the bigger picture: Bitcoin is the larger, simpler asset. Ethereum carries extra upside and extra risk tied to how much its platform gets used.
Questions people ask
What is the main difference between Bitcoin and Ethereum?
Bitcoin is a digital currency with a fixed supply of 21 million coins. Ethereum is a platform that runs programs called smart contracts, with ether as the fuel that pays for them and no fixed supply cap.
Does Ethereum have a supply cap like Bitcoin?
No. Ethereum has no fixed maximum supply. New ETH is issued to stakers, but part of every transaction fee is burned, which can offset issuance and occasionally shrink the supply.
What was the Ethereum Merge?
The Merge, completed on 15 September 2022, moved Ethereum from proof of work to proof of stake, cutting its estimated energy use by about 99.95%.
Is Ethereum more volatile than Bitcoin?
Over the year to 14 November 2026, yes. Ether's median daily move was 1.38% against Bitcoin's 1.16%, and it had 34 days of 5% or larger moves compared with Bitcoin's 18.