Both use similar technologies, or are at least crypto-currencies using ledger technology other than blockchain.
Nano seems to be the most of the two with more activity in the current new cycle, Binance trading, Rebrand but also FUD regarding Bitgrail Fiasco.
If the assumption that IOTA might be following NAno is true, IOTA is about to see another pump cycle soon.
Please let me know your thoughts and comments guys. What do yall think of DAG and Tangle?