To be honest with you, there is no other coin/s similar to Bitcoin and that is why the rest coins are called altcoins.
We don't need to specify the difference among them but you will just fail if you keep looking at it. Instead of finding and searching for coins that similar to Bitcoin better to spend that time knowing more about crypto and to find which is the best coin/s for investment. If Bitcoin is not your choice, make some selections on the top 20 altcoins, not by looking into new projects.