Bitcoin is a decentralized digital asset — arguably, the most popular — and typically takes up half of all digital asset trading volume on most given days. Bitcoin utilizes blockchain technology. Blockchain is not a cryptocurrency. It is the ledger that records all the cryptocurrency transactions that are verified by cryptography and is open, secure and accessible by all.
Anyone can make a transaction and sign it with a private key. It will be broadcasted to the unconfirmed transactions pool and be verified by miners who will get the fee from it as a reward.
Each new block with transactions is approved by a consensus mechanism and cannot be reverted after a certain amount of time (six blocks for Bitcoin).
The main difference is that Bitcoin has proof of work (POW) consensus and also uses a specific model of transactions. Blockchain technology does not have any strict restrictions on consensus, transaction model and data that will be transferred in it.
For example, enterprise blockchain systems are used to build the supply chain without any financial data in it.