The Galaxy S9 has better speakers.
With the Galaxy S9, Samsung added a second loudspeaker in the phone's earpiece, which creates stereo sound — something the Galaxy Note 8 doesn't have.
Smartphone speakers aren't often known for their sound, but multiple critics have pointed out how great the Galaxy S9 sounds when you're playing music or watching video.
The Galaxy S9 has a more advanced camera.
Samsung added a new feature to the Galaxy S9 called Pro Mode. The phone can toggle between two different apertures automatically depending on how much light is present, or you can manually adjust the aperture like on a DSLR camera.
The Galaxy S9 also has a new "super slow-mo" mode, which lets you shoot HD slow-mo videos and turn them into GIFs.
The Galaxy Note 8 has an incredible camera too — dual lenses, 2X optical zoom, the ability to save images as RAW files, and Samsung's version of portrait mode. But the Galaxy S9 is just slightly more advanced.
The Galaxy S9 runs a newer version of Android.
The Galaxy S9 comes standard with Android 8.0 (Oreo), while the Galaxy Note 8 runs Android 7.1.1 (Nougat).
The Galaxy S9 has a more smartly placed fingerprint sensor.
One of the most irritating issues with the Galaxy S8 and Galaxy Note 8 was the placement of the fingerprint scanner — right next to the camera lens.
Users complained that it was hard to reach, and that when going to use the fingerprint scanner, they'd inadvertently smudge their camera lens.
With the Galaxy S9, Samsung moved the scanner to below the camera lenses, which means it's easier to reach — and you no longer have to worry about a smudged camera.
The Galaxy S9 comes in more colors.
If you're someone who likes a few color options when picking out a new phone, you won't find that with the Galaxy Note 8. The phone only comes in two colors — midnight black and orchid gray.
The Galaxy S9 has four color options: lilac purple, midnight black, titanium gray, and coral blue.