The correct term is Bitcoin Blockchain, not Bitcoin Timechain. There is no functional difference between the terms, but the vast majority of the Bitcoin community uses the term "blockchain" to describe the decentralized ledger used to keep track of all Bitcoin transactions.

A blockchain is essentially a decentralized, distributed ledger that keeps track of all transactions in a given system. In the case of Bitcoin, the Bitcoin blockchain serves as the public ledger for all Bitcoin transactions.

In order to add new transactions to the Bitcoin blockchain, nodes on the network use a consensus mechanism known as mining to verify new blocks of transactions. These blocks contain a record of all recent Bitcoin transactions and are cryptographically linked in a chain - hence the name "blockchain."

Overall, the Bitcoin blockchain is an incredibly important part of the overall Bitcoin ecosystem, as it serves as a key component of the decentralized, trustless system that makes Bitcoin transactions possible.

There is not such a thing like Bitcoin Timechain