what is the different between bitcoin,altcoin and ethereum?

[Elyenlayna]

Bitcoin was the first cryptocurrency and the
strongest all other coins like Ethereum etc that came after fall under
 Altcoins (alternate coins).
 

[patron bounty]

Bitcoin is an electronic money made in 2009 by Satoshi Nakamoto. The design of Bitcoin allows for anonymous ownership and transfer of wealth.
The length of Altcoin is alternativecoin which means coin-coin other than bitcoin.
Ethereum is a public peer-to-peer network or a blockchain with its own digital currency called Ether