I think the difference should be noticeable but even this depends on how you like it. Simply the more the ratio is the stronger the colour appears or
a difference of 40 % should be always noticeable as it is a big difference but that value alone doesn't mean the screen is less or more easily readable. If you think what it means a value of 1 of contrast ratio should mean that colors are indistinguishable one from another. Important factors are the degree of screen reflectiveness, the type of panel used in the display and the value of brightness. The different panel technology can make use of less layers thus raising the clarity of the image, for example ips is thicker than amoled as it uses more layers but i don't know wich they are and what are the function of them right now. This causes more reflections because the light passes trough more layers. From the readablity point of view the brightness is a major factor as it seems a value of around 500 is very good for reading in bright environments but again it also depends on your liking because for example a friend of mine who possesses a galaxy j3 2017 had to manually turn down the brightness after setting the adaptive brightness off because it was uncomfortable with it out of the box. Finally there may be certain specific techniques used for producing certain smartphone displays on wich i don't know much but for example sometimes a technique called full lamination is used and it reduces consistenlty the space between the display and the external glass making the display seem like it is painted.

The screen measurement differences, when compared to Honor 9 Lite, seem pretty big, for example contrast (910 vs 1529). I know that P smart comes with a screen protector applied, I presume it was taken off for measurements, right?
Is the difference so noticeable also in "real life", for example outdoors?

SAR Values???