A hobby of mine is spherical panorama photography.
The ultra wide angle Olympus 4/3rds Zuiko Digital 8mm f/3.5 fisheye lens mounted on my Olympus E-P1 allows 360° in all directions to be captured in just 7 (or 8) shots.
Shown here attached using a 4/3rds to micro-4/3rds adaptor.
As is standard, I shoot one row around using 6 shots (every 60°) in portrait format for maximum vertical coverage, plus 1 zenith and optionally one nadir. This provides decent image overlap for stitching.
The Panasonic Lumix G Vario 7-14mm f/4.0 is a rectilinear zoom lens that is quite compact and light by comparison. It's actually nearly half the weight: 300g vs. 568g = 485g + 83g for the Olympus MMF-1 adaptor. However, the maximum diagonal angle of view is spec'd at 114° vs. a claimed 180° (computed 170.2°).
See http://slash72.club.fr/gurl/Olympus/Copy%20of%20fisheye.htm for the Olympus 8mm fisheye technical details.
Let's compare the true coverage of the Lumix rectilinear lens at 7mm against the Olympus fisheye (8mm).
Pictures below were taken at Yodobashi Camera in Shinjuku.
Landscape format
Lumix (@ 7mm):

Olympus (fisheye):

Olympus Studo (fisheye correction):
Compare the coverage in the above image to the Lumix 7mm image shown earlier. The fisheye is definitely wider. And actually, the fisheye image extends beyond the rectangular portion at the corners. See below.
Olympus (defished):

The defished shot above was created using Turk's
free defish program with the following parameters:
Seems like the aspect ratio is a bit off. One of my parameters must be a bit wrong. Oh well. But you get the idea about the extra coverage.
In spherical panorama photography, the shots are taken with the camera rotated into portrait position.
Portrait format
Lumix (@ 7mm):

Olympus (fisheye):

Olympus Studo (fisheye correction):

Olympus (defished):