ue4 what does specular do code example

Example: ue4 what does specular do

Roughness shows how sharp or blurry the reflections are while
specular shows how noticable or how bright they are. 

In other words, specular doesnt change how the reflected image
looks but a low specular would make it very subtle and hard to 
see while a high one would be very noticable (almost like a 
transparancy value for the reflected image).