So, just actually getting your dollar from the bank, rather than keeping a promise of a dollar from the bank. Doesn't seem much different today, right? But it might tomorrow.
In the days of the gold standards, a dollar was defined as a coin with certain specifications — including a specific quantity of fine gold. The problem inevitably arose, under these various forms of gold standard, where enough people demanded what had been specified, the banks were unable to deliver it to all of them as promised. This was inevitable, because money is not gold… money is credit.
People take out credit for all manner of things, with no regard or connection to the availability of gold to physically make all that money into coins for all the Negative Nancies out there who suddenly decide… Hey, wait a minute! I don't trust the bank's promises any more!!
Fortunately, today the dollar (or any other currency) is not specified as something physical that can be demanded — except for demanding a physical piece of paper with 'dollar' written on it from the bank, which you can hand to someone for their goods, instead of paying with your bank debit card or cheque, and they can pass on to someone else in the same way if they wish, or just pay it back into a bank again. Ultimately, it ends up either under a mattress or back inside the banking system… since it's useless for much else besides perhaps lighting a cigar, or wrapping a piece of used chewing gum before you can get to a waste receptacle.
Almost nobody believes money is gold today… meaning that almost everyone is right, which makes for a pleasant change!
You may not like it, but not everyone agrees.