Ethereum and Bitcoin are the two most popular blockchain platforms in the world today, but have two different goals.
Bitcoin is the “gold standard” of blockchains.
It’s been around for the longest, and its protocol has successfully supported an enormous number of transactions over the past years.
It’s intended purpose is solely to allow the transaction of bitcoins, its native asset.
On the other hand, Ethereum is a smart contract blockchain platform, a distributed world computer.
It’s native asset ether exists to fund computation and to align incentives.
Its primary purpose is not to act as a medium of exchanging value.
Bitcoin is simple and robust.
It’s a global payment system.
That’s all it really sets out to do.
Ethereum has a much larger vision, and therefore supports many more features, for example, a much more powerful scripting language.
Bitcoin has a stack based primitive scripting language which is not turing complete, meaning that the applications we can make on Bitcoin are pretty limited.
Ethereum on the other hand has a Turing-complete scripting language — one of the motivating factors for Ethereum’s creation in the first place.
So, a wider variety of applications can be made on Ethereum than on Bitcoin, making it more developer friendly.
Another key difference is that Bitcoin is UTXO-based, whereas Ethereum is account based.