- Software wallets such as Metamask and Coinbase Wallet exist as programs/browser extensions on your devices and often are partly custodied with a third party
- Hardware wallets like Ledger and Trezor run on physical devices with your private keys stored on the device instead of your connected devices or online
- Connecting a hardware wallet to a software wallet like Metamask allows the hardware wallet to be used as a 2FA device requiring you to approve transactions both in the software and on the physical device
- Using the combination of a Software and Hardware wallet allows you to conveniently access your favorite dApps without compromising on security
References
This fantastic Guide from Ledger goes into the step by step process required to connect your Ledger Hardware wallet to your Metamask Software wallet:
https://www.ledger.com/academy/how-to-secure-your-nfts