The lens comes with free gopro case.

What’s the difference between
the 1/1.8 and the 1/2.3 lenses?

Both lenses are 4K

The 1/1.8 allow in more light.
The downside is that you cannot close the ‘GoPro’ lens cover and it’s more expensive.

The 1/2.3 lenses allow less light through.
The upside is you can close the lens cover and it’s less expensive.

Please note: The gopro it’s not included just to show how will be looks after fit the lens.