Make mesh and 2d sprite have same color

the snowman is a sprite with Sprites/Diffuse shader, while the ground is combined mesh with Standard shader. Both supposed to have the same white color.
What shader should i use to make their color same, even after receiving light?

 

The standard shader and the sprite diffuse shader are using very different lighting models. You want to use "Legacy Shaders/Diffuse" for the non-sprites if you want them to match.