Bitcoin is a cryptocurrency that derives its value from its brand name. It is the oldest crypto on the market. Technically it is a store of value like any currency. Its value is derived from its limited production. The total supply of Bitcoin is around 17 Million which can be mined.
Steem on the other hand aims at building a decentralised block chain for a social network like Facebook, Youtube,twitter etc. Its supply is much more than Bitcoin.
The biggest difference between Steem and Bitcoin is that Steem derives its value because of its use. Its practical applications provide it, its value. Thus it would be unjust to compare Steem with Bitcoin. Even though both are based on the Blockchain but both differ in nature completely.
In a common easy to understand language comparing Steem and Bitcoin is like comparing the Sun and Moon.
STEEM is a blockchain-based digital currency, like bitcoin, that allows users to store, send, and receive digital payments. However, Steem is not mined like bitcoin, nor is it intended as a spending currency. Instead, Steem is earned on the Steemit social media network through contributing to the platform