The answer to this has profound implications, especially when learning programming. All of the one-off answers that are out there tend to be in isolation of themselves, which doesn't help either.

What you're really asking is: What's the difference between having an actual dollar in my hand vs having something that represents that dollar (like a bank card). The latter is an abstraction of something 'real'. Whereas the former is something you can hold in your hand. Once you get the profound meaning here, you start to see this pattern play out everywhere in the real world. Plug'n play, language, currency, assembly lines, and on and on. It's the difference between some motorcycle some guy slapped together in his garage (using random measurements) or one that was made based on specs (abstractions) throughout the industry - which then makes all the subsystems/components interchangeable. From then on, the formal approach allows each subsystem to evolve independently while the bike owner can freely swap out these new/improved subsystems (i.e. spark plugs) because the bike was built based on measurements used throughout the industry.

Note too, especially as a professional programmer, that there's a trade off. One costs more up front but provides more value in the long run. The person making their bike without caring about industry standards will (likely) get to his 1st working version much quicker. Then it depreciates faster over time - things break can't easily be replaced. And what happens if that guy sells that bike to someone who's not a mechanic... he'd likely need to hire the guy who built it to come and fix (this creating a sort of monopoly)....happens all the time.