CobaltKobold: We've got both that a Door is made of Wood, and that it is made out of Glumprong. That means Marble Tables can, eventually, look like Marble Tables, and be visually distinguished from Andalusite Tables, and Rock Salt Tables (the table that seasons food automatically!) Same goes for naturally occuring stone... so we aren't limited by stone color or type, but can have different textures for every one.
It shall be glorious.
Natural Stone (Smoothed)
Raw Stone (Cobblestones)
Stone Blocks (Bricks)
Raw Wood (Trunks/Branches)
Wood Blocks (Planks)
Metal (Forged Bars/Plates)
Glass Blocks (Carved/Shaped)
Your 'natural stone' look likes constructed stone blocks. Your 'raw stone' looks like a 'rough' constructed stone wall from raw stone, not blocks. The stone block one is just odd, you have tiled bricks on the sides but the top is a grid?
I would use the first one 'natural stone' for constructed stone block walls, the 2nd one for constructed walls from natural stone. The third one could probably be reworked for glass blocks, as I don't see them casting one huge glass block for a wall. Raw wood is fine as-is, or you could make them stacked horizontally. Either one works. The wood blocks you have there look fine. Just my 2 bits, great work overall.
"Natural" Stone should have been labeled Smoothed Stone; regardless, its one I'm having the most trouble properly representing. It is what texture results when plain stone layers are Smoothed by engravers. The blocklike texture is meant to be lines carved directly into the wall, rather than something that the dwarves have built up, to add a sense of texture. The major reasoning was to differentiate between actual Natural stone and Smoothed Stone, which are tough to show when dealing with neatly differentiated cubes of stone.
Raw Stone is used for walls built from plain hunks of stone that miners have mined, without any sort of processing, IE a mortar and cobblestones. Walls like this have been done for ages prior to brick-based masonry techniques, and they require less work, but are as a result less strong and fall apart sooner.
Stone Block walls are, in my mind, made of cut Bricks and Mortar; they're what results when you take the little raw stones you've mined out, and process them into neat blocks before deciding what to do with them. As you can see on the top, the bricks themselves are Square, not Rectangular, and the "Grid" you're seeing is a 3x3 checkerboard etching done to allow them to seal better with the brick above, and most importantly to make the floor more visually interesting.
There is method (and in some cases, historical research) to my madness.