yes that is the result of "SUM(B:B)" in the CSV file, and I did some search afterwards and it seems like the chart on blockchain.info is not quite clear! in fact there is the exact same question being asked here:
https://bitcoin.stackexchange.com/questions/46346/how-can-the-number-of-unique-addresses-decline
if you look at dates and number of addresses (column A and B) there has been 14 addresses used until 1/9/2009 which is this block https://blockchain.info/block/0000000080f17a0c5a67f663a9bc9969eb37e81666d9321125f0e293656f8a37 with height 14 or 14 coinbase transactions or 14 addresses with balance in them. that is why I simply added the numbers.
Based on the first blocks the number of unique addresses is indeed that for the first days as each generated address was used for the first time.
Blockchair is a better tool for this
https://blockchair.com/bitcoin/transactions?s=time(asc)
Yeah, you were right, that's the number of unique outputs:
https://blockchair.com/bitcoin/outputs?s=value_usd(desc)