Hmm, it's a bit technical mate. Pero ganito yun:

Ang "blockchain" ay ginagamit para i-describe yung overall na technology kung saan naka-store ang data ng Bitcoin transactions.

Yung term na "timechain" naman, ginamit ko lang 'to dati sa original whitepaper ko to describe the concept of blockchain.

Pero generally, they refer to the same thing - yung chain of blocks containing transactions in the Bitcoin network.