The Cardano blockchain is a 3rd generation blockchain platform that was designed with a collaborative peer-to-peer review system, It aims to improve upon prior blockchain systems to enable larger and more sustainable uses of the technology.
Cardano was built with a governance model that is based on collaboration. This allows the platform to evolve quickly and adapt to the changing needs of its users. Unlike many other blockchain projects, it also installed a treasury system to fund the ongoing development needs that may arise as it moves forward.
The Cardano blockchain uses a unique proof of stake algorithm called Ouroboros and has a protocol that consists of two layers, a settlement layer and a control layer. The settlement layer is designed to perform accounting functions, while the control layer is tasked with running smart contracts. The platform tries to balance the privacy concerns of users with the requirements of regulators in an effective way.
Cardano uses the Haskell programming language and is fueled by the ADA coin

Bitcoin is the first digital currency based on blockchain. It solved the double-spending problem and enabled peer-to-peer transactions on a large scale. Bitcoin was designed to work as a trustless digital currency that would function without government oversight or a central bank.
Bitcoin was developed by Satoshi Nakamoto, whose identity has never been confirmed and has become the subject of great intrigue. Bitcoin builds upon on other cryptographic and digital currency projects that came before it, but its use of blockchain made it more viable. Nakamoto originally released his white paper and open-source software on a cryptography forum. He mined the first block of the Bitcoin chain, called the genesis block in January 2009.
Bitcoins are created as a reward for a process known as mining. One of the core innovations of Bitcoin, is its consensus algorithm, which creates an incentive system that rewards miners for confirming transactions.
Hal Finney, who developed the first reusable proof-of-work system (RPOW), several years before, was the first Bitcoin adopter and received the first bitcoin transaction ever recorded on its blockchain.

NEM is a cryptocurrency and blockchain platform that allows multiple ledgers on the same blockchain. NEM Smart Assets are used to create mosaics for any asset. Transaction fees are paid with NEM's native currency, XEM. NEM originally began as a community-oriented cryptocurrency that was built from the ground up in the Java programming language.
NEM's goal is to achieve widespread distribution through improved scale and speed. It pioneered several blockchain features such as its proof-of-importance (POI) consensus algorithm, encrypted messaging, a unique reputation system, and multi-signature accounts.
NEM is also developing a commercial blocckahin called Mijin, that is currently being tested by several companies and financial institutions.
In early 2018, approximately $400 million worth of XEM were stolen from a Japanese exchange called Coincheck, that was the victim of huge hack. The exchange failed to implement proper security for this coin protocol, and the hackers only stole XEM coins as a result. Instead of creating a fork to deal with this issue, NEM set up an automated tagging system that flagged these funds. NEM then stopped tracking these stolen coins