The Galaxy S10 has three camera options. The Pixel 4 has two, and it's missing the one camera it should have had.
The Galaxy S10 has an ultra-wide lens, a regular lens, and a zoom lens.
The Pixel 4 has a regular lens and a zoom lens — it's missing the ultra-wide lens. The Pixel 4 might take better photos in overall, at least from the regular and zoomed lenses. But it can't take ultra-wide photos, which means the Pixel 4's camera is significantly less versatile than the Galaxy S10's.
If you like to record video with your smartphone, the Galaxy S10 has much better quality and options than the Pixel 4.
The Galaxy S10 can record 4K video up to 60 frames per second for a smooth video. It's actually become a fairly common option in many top-end smartphones, but Google is neglecting the video recording part of the Pixel 4, which can only record 4K video up to 30 frames per second. That's fine, but it's not as comprehensive as the Galaxy S10.
The Galaxy S10 can also record video in HDR10 Plus for better colors and contrast, whereas the Pixel 4 doesn't offer that option.
It's not a massive deal, nor is it a deal-breaker. But the Pixel 4 certainly shouldn't be the phone of choice for those who care about video recording.