One bitcoin is one bitcoin, exchangeable for another in a fully fungible manner on global exchanges that operate 24/7, 365 days a year.
But in Over the Counter (OTC) markets, there are different flavors of bitcoin with the oldest one being ‘clean’ BTC.
That conceptually arose when the US government auctioned 144,000 bitcoin in 2014 and 2015 after seizing them from the Silk Road market.
The suggestion was that since these bitcoins came from the government, there are no concerns of them having been used for illicit activity, and thus in theory demand for them should be higher than for other coins.
