Zcash (ZEC) is a cryptocurrency with strong cryptography that is supposed to provide high security and privacy. At some point, Zcash was endorsed by Edward Snowden and Roger Ver. Zcash is a Bitcoin fork and it exists since 2016. The mechanism providing privacy is called zero-knowledge proofs (or zk-SNARKS).
Dogecoin (DOGE) was founded in the US in 2013 as a joke but quickly gained a large following. It became a popular cryptocurrency (DOGE) used for tipping the content creators (mainly on Reddit and Telegram). As the creators had no serious plans for their currency they didn't elaborate a roadmap and were not working on the improvement of their project too much. The founder of Dogecoin Jackson Palmer left the project in 2015.