HD wallet stands for a Hierarchical Deterministic wallet. The difference is that a new wallet is generated with a seed phrase consisting of easy-to-remember words (instead of a private key made of random digits).

In most cases, a seed phrase includes 12 words. OWNR wallet allows youto generate seed phrases of 12/15/18/24 words in 8 different languages.  

Creating or restoring an HD wallet is much simpler compared to other wallet types. Moreover, you don’t have to create a wallet for each coin - all wallets for all coins are generated with one seed phrase.

You may learn more about HD wallets here.