To me the biggest difference is how bitcoins are created. It takes a great deal of investment in time, effort, money and energy just to mine and produce a single bitcoin.
Unlike altcoins, you can't just print a bitcoin out of thin air whenever you want. Any idiot with a PC can create a new crypto altcoin and print an unlimited or nearly unlimited supply for himself to dump onto the market, whenever he wants. But that's not how bitcoin works.
Imagine having a money printer that prints an unlimited amount of dollars anytime you want. You don't have to do shit to earn it. Just enter the amount you want and press the print button. Voila! You are instantly rich. That's basically how garbage like dogecoin, ethereum, solana, XRP, fartcoin, pepecoin, clowncoin, etc. all work. They are just a digital recreation of the unlimited fiat money system but worse, with no discernible value beyond being a high-tech Ponzi scheme.
What are other differences?
"Printing money" is easy with tokens because you don't need any coding/technical knowledge to launch your very own scam coin. But in Blockchains made from scratch (native cryptocurrencies), it's another story. Although, anyone can create a clone off Dogecoin or Bitcoin's codebase and launch it for his own benefit. But you'd have a hard time convincing centralized exchanges to list your coin. With tokens, it's much easier because decentralized exchanges don't have as many requirements as centralized ones.
Anyways, the biggest difference between Bitcoin and altcoins (besides the supply) is that BTC is decentralized, while most other coins are centralized. Security and reliability is what makes Bitcoin a "winner" among the rest of the pack. Bitcoin also has an anonymous founder/creator, which makes it truly censorship-resistant. Not like the zillions of "shitcoins" you see out there with publicly-known founders. Everybody knows ETH was created by Vitalik Buterin, Cardano was created by Charles Hoskinson, Tron was created by Justin Sun, and so on. This creates a single point of failure as governments will be able to prosecute such individuals to meet with their demands. Why do you think nothing can beat the "King"?
