Afaik at some point in 2014/2015, Bitcoin became known as 'Bitcoin Core'. I assume this was to differentiate it from other implementations of Bitcoin.
When and how did this decision come about?
The renaming was merged in December 2013 with prior discussion on this GitHub issue. The general motivation was to distinguish between one particular implementation of the Bitcoin protocol (many refer to Bitcoin Core as the "reference implementation") versus other implementations (libbitcoin, btcd, bcoin, bitcoin-s etc) that either existed at the time or came later.
At the time most of the well known altcoins (Litecoin, Dogecoin etc) didn't hard fork the Bitcoin blockchain. They started their blockchain from a different genesis block to Bitcoin. The well known hard forks came later in 2017 with BCH, BSV etc.
As MCCCS commented, https://github.com/bitcoin/bitcoin/issues/3203 covers this
Rebrand client to 'Bitcoin Core' #3203
laanwj opened this issue on 5 Nov 2013 · 23 comments
laanwj commented on 5 Nov 2013
To remove the confusion between the Bitcoin network and the reference client implementation that we maintain in this repository, both confusingly named 'bitcoin', we'd like to rebrand the client.
This has been discussed a lot before, but the following is the proposal by @gavinandresen and I agree:
Bitcoin-Qt --> btcore (full name 'Bitcoin Core') bitcoind --> btcored (full name 'Bitcoin Core Daemon') bitcoin-cli --> btcore-cli (full name 'Bitcoin Core CLI Client')
Renaming the executables is going to break some scripts, so we'd likely want to combine it with the bitcoind CLI deprecation to make sure the migration pain is short and swift instead of drawn out.
So the primary motivation seems to have been to avoid having the one word "Bitcoin" refer to both of two very different things - the network of Bitcoin nodes and a specific software implementation (one of many).