I have the Exynos S9+ and I use the camera a lot, especially macro shots in pro mode.
I have noticed that there is a few centimeters difference in the closest distance that the camera can focus between the manual and auto focus.
With the auto focus or 'tap to focus' I can get as close as about 5.5cm
With the manual focus when dragging the slider all the way down I can only get about 9cm (this distance should also be 5.5cm).
I know it doesnt seems much but when taking macro shots 9cm vs 5.5cm is a lot and it makes the manual focus useless for me.
I have tested this with a friends S8 and both its camera's auto and manual focus modes are having a good close focus distance of 5.5cm.
I have also posted this problem on reddit and it seems only the Exynos models are having this issue:
Hopfully someone from samsung can help with this.
Here are some images to show the problem: