Well, is nice see the new Roughness Material setup because many material libraries and apps use Roughness maps, but the new Roughness Material setup have not control for Smoothness (or Roughness) like the Standard Material setup, please add this control (a intensity value slider), thanks.
Isn’t roughness just the invert of smoothness? (I actually don’t know)
it would be convoluted to have two controls for the same thing
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Roughness is the opposite of Smoothness both shaders have controls for the contribution so both works the same.
The only difference is that the Standard shader has the Smoothness map packed in the Metallic Alpha, while the Roughness material has each input map separate.
No, both not works the same, the standard shader can control the Smoothness with a slider bar, Roughness setup does not have this control, which version of Unity use you? When you load a image for Roughness in the standard material (from albedo or metallic alpha) this slide bar control dont dissapear, the value control the intensity of the map (unlike the metallic maps the metallic slide bar dissapear when a metallic map is loaded).
The old standard shader assumed you had the roughness in the alpha channel of the metallic map. The smoothness slider was simply a multiplier of the alpha channel if that was the option you had selected. If the alpha was empty it basically became the roughness value. And to the poster above, generally speaking depending on verbiage, yes roughness is essentially the invert of smooth. Honestly I’m not sure why they split them out in the newer standard shader as that seems like a step back to me. The take away from this is that the smoothness slider you are asking about was only a multiplier for the roughness alpha packed into the metallic map. Much like there are multiplier sliders for normal maps to increase intensity.
but the new Roughness Material setup have not control for Smoothness like the Standard Material setup, please add this control, thanks.
The “Standard (Roughness setup)” matches the parameters of the Autodesk Stingray PBS shader (might also be called Interactive PBS in the latest 3DS Max) so that we can import it from FBX. We caution using this shader in production - it has higher resource requirements than the regular Standard shader due to the separate roughness map.
Here’s a video demonstrating how to bring 3D models using the Stingray PBS shader into Unity: Recorded Video Session: Importing 3D Art into Unity - Unity Learn
Honestly I’m not sure why they split them out in the newer standard shader as that seems like a step back to me.
In the long-term, Shader Graph and SRP will replace the legacy rendering pipeline and shaders. We needed a solution for 2017.x, though, and the Singray PBS was the only PBR shader available across Maya, Maya LT and Max. We’re working with Autodesk on a better solution, but material transport between renderers is a hard problem.
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Thanks for the detailed explanation.
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Introducing smoothness was a pure hipster move from Unity, should’ve been roughness like the rest of the planet. Please migrate to industry standard terminology for the benefit of every existing and future Unity users 
Phase out inverted roughness and just have roughness for all shaders over time. At minimum it doesn’t freak out artists migrating from other engines and reduces friction in engine adoption while increasing communication quality as we don’t need to talk about one minus.
When it dawned on me that Unity wanted to be hipster and introduce inverted roughness and call it smoothness for zero performance benefit, I actually felt slightly confused. That would not improve shader performance, so why would you confuse the entire planet that is used to using roughness as terminology and make more friction points in authoring content?
Throws wacom pen.
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I actually like smoothness over roughness, and a few other AAA game engines use smoothness as well like Infinity Ward on Infinite Warfare. Switching from old gen texture workflow to PBR with roughness, you had to get used to making a roughness but smoothness was/is basically a gloss map so my brain was already used to that. This was/isn’t a problem though but more of a preference.
They will probably be making a roughness version of the standard shader since it will need to work with FBX Exporter/Importer Round Trip workflow with the Stingray shader in Max and Maya. It would also be nice to have it in the shader graph as well for those who want to use it in custom shaders.
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I always remap smoothness to roughness because of using substance designer and other programs that follow standards, but yes its a pain doing this everytime for just this one engine
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