Comet (CMT) cryptocurrency is formally accounted on the number of ratings.. However, there is no up-to-date official information about its current status. Therefore, we can conclude that the coin is currently inactive.
Dash was launched in 2014 and changed several names before becoming Dash as we know it today. The initial goal of the project was to create a cryptocurrency network which would operate faster and cheaper than Bitcoin and would be capable to maintain more privacy. Holders of large amounts of Dash have different privileges (Instant Send, Private Send, etc).
Dash is an open-source project. It has its own blockchain. The currency is supported by many crypto wallets and it has gained significant market capitalization. Another great achievement is its numerous partnerships including cooperations with Western Union, web stores, etc.
IoT Chain (ITC) operates both on cryptocurrency Ethereum protocol as an ERC-20 asset and as a coin on its own mainnet. The ITC cryptocurrency is widely represented on the Asian exchange platforms paired against other cryptos.