There is a difference in the quality of lighting when using Preview vs Production. This difference is changing the number of indirect lighting bounces and other lightmass settings to give you a “preview” of what the lighting will look like. It will inherently be inferior to building lighting with Production. There tends to be more light leaks and less accurate shadows. Think of this like the Engine Scalability settings except for Light Builds with Lightmass.
In your first image This looks like you’ve already built the lighting on the Preview level possibly. The error here is that it looks like your light is sitting partially in the wall causing part of the mesh to project a shadow inside that should not. You would need to move the light outward more so that it’s not penetrating the wall in such a way. If you’re wanting to use something similar to a fluorescent light try adjusting the Source Radius and the Source Length of the point light into the shape of a tube light.
In the production build it’s some of the same things as mentioned above. A lot here can also be determined by your UV layout and how light is being handled on the surface of an object. This leads directly into Lightmap resolutions playing a large part of you static lighting quality as well.
Here are some examples I’ve setup to hopefully demonstrate some of this for you.
Lightmap UV Layout
Lightmap resolution set to 128 unless specified otherwise
Preview Light Build:
Production Light Build:
If you’ll notice there is still some bleed that is coming from the light that is affecting the front of our light housing above the door.
If you adjust the Indirect Lighting Intensity and change this to a value of 0 so that there is no GI contribution or even a very low value you can get better results that give a more natural look.
Indirect Lighting Intensity 1 (Default)
Indirect Lighting Quality 0
Emissive Lighting used as static lighting bakes the lighting directly into the lightmap. So this can directly affect the object where lighting is baked if the light map resolution is not high enough and if there is not a good UV layout for the lighting to be baked at a decent quality.
LM Resolution 64
LM Resolution 256
LM Resolution 1024
As you’ll notice the smoothness of the emissive lighitng increases with the lightmap resolution. While this may produce better results it also means that more texture memory is being used. This is not an ideal use case for emissive lighting as static lighting necessarily. You also don’t have control directly over how the light is baked as you do with static lighting.
Please take a look at our Wiki Lighting Guide for more common lighting issues as well: wiki.unrealengine.com/LightingTroubleshootingGuide
I hope this has been helpful.