I have a few files that I thought were set up with the same materials and settings.
However, when I export & open in another program (X-Plane), some are shiny (reflective or glossy) and others aren’t.
I’ve looked through them, and not found my error… is there a way to compare materials from two different files?
If there’s a way to somehow export a text file of each, I could do it that way, too.
thx
How some undefined materials look in other software has nothing to do with Blender. Different software and rendering techniques look different in many aspects - the materials themselves, light calculations, tone mapping, even color management for textures may be different so of course there will be differences.
just open the 2 files in 2 instances of blender. then you can compare them
You can export to obj with material that gives you an textfile. But that can you only tell which are not identical, not a sure way to say they are identical. For that you need to white a python script thats compares the material nodes. And even than you have to compare texture and attributes.
Example mtl file from obj export
# Blender 4.2.0 MTL File: 'untitled.blend'
# www.blender.org
newmtl hereiam
Ns 250.000000
Ka 1.000000 1.000000 1.000000
Kd 0.800000 0.800000 0.800000
Ks 0.500000 0.500000 0.500000
Ke 0.000000 0.000000 0.000000
Ni 1.500000
d 1.000000
illum 2
newmtl hereiam.001
Ns 0.004000
Ka 1.000000 1.000000 1.000000
Kd 0.800000 0.800000 0.800000
Ks 0.500000 0.500000 0.500000
Ke 0.000000 0.000000 0.000000
Ni 1.500000
d 1.000000
illum 2
I am pretty sure that’s not a meaningful solution to ANY possible problem. 
Blender’s OBJ exporter will not export anything even close to possible materials used in Blender. It’s not too difficult to write a Python script to compare certain aspects of materials, but Turner hasn’t formed the question in a manner specific enough to help with that yet.