It is completely different. True, at one point in time, what we called the dollar was a fixed weight of silver. Back then, fractional reserve banking was not pervasive - at least not at a federally-sanctioned, pervasive level. However, after the founding of the FED, there was a program unfolded over decades that got us off of that definition of the dollar and onto its current definition. It is now not a fixed weight of silver, but rather a federal reserve note of no fixed measure. These federal reserve note 'dollars' for which we grub are already nothing more than an IOU. There is no discernible difference between the IOU in paper form, and the IOU in terms of transferable bank balance. In either case, the backstop for the paper IOU and the bank balance IOU is the FED.

In the case of Bitcoin, OTOH, there is a distinct difference between the Bitcoin itself (i.e. you and you alone have the private key that enables transferring the associated value) and a Bitcoin IOU (i.e. the bank has the private key {unless they have loaned it out}, and you merely have the bank's word that they'll give you the associated Bitcoin when you ask for it).

I really don't see how this distinction is hard to grasp.

You'll need to expound upon your point before I agree with you that 'if the pervasive central banking system is a scam, then so is Bitcoin'. I really don't see it that way at all. Indeed I see no correlation whatsoever. Sure you can point to various scams in Bitcoin-land - but these are each single failures. They are not institutional. They are not endemic to Bitcoin. In contrast, the wealth-stealing nature of each and every central banking edifice is systemic in nature, and an integral foundational concept upon which the system is predicated.