How is bitcoin different from all the other cryptocurrencies?
Unlike the world's traditional money systems, bitcoin is a financial system that nobody can control. Also, nobody can create more bitcoins once their number reaches the predetermined cap of 21 million; and nobody can seize it, steal it, manipulate it, etc. In short, bitcoin is a decentralized protocol.
It's different from the other multiple thousands of cryptocurrencies in that it is not controlled by anybody. It is completely decentralized.
The key aspect that makes bitcoin decentralized (versus the other 15,000 or so cryptocurrencies) is that its database is very small. It's about 300 gigabytes (e.g., you could run it on a thumb drive). And the reason that this is important is because it means that you can run a node.
Just to frame this up real quick, something like Facebook or Experian is on a centralized database, and because Experian is on a centralized database, it gets hacked all the time. On the other hand, bitcoin is a decentralized database. That means instead of one database, there are millions of databases, meaning that you can run a full copy of the bitcoin database. You can do it on an old laptop, or on a Raspberry Pi, etc. Anybody can buy one, or build one for a hundred bucks, and run it.
The problem with all the other thousands of cryptocurrencies is that you cannot do this with them. So, if you look at etherium, cardano, etc., you basically have to have an industrial grade server co-located in an industrial grade co-location facility. So, it blocks the average person from a node, which of course causes centralization!
This is probably the biggest difference between bitcoin and all the rest.