Complex sentence: The "hw" interface provides direct access to the kernel device, however, no software mixing or stream adaptation, while "plughw" or "default" enables sound output where the "hw" interface would produce an error.
Split into simpler sentences: The "hw" interface provides direct access to the kernel device, but no software mixing or stream adaptation support. On the contrary, "plughw" and "default" enable sound output where the "hw" interface would produce an error.