LHS:

The Gradient Shading. I tried several tools on AI illustrator to test various colours and shading. 

For all the 3 shapes I used the gradient colour of yellow to orange. It turns out to be a sunset, I guess?

RHS:

The Vector Shading. After Ctrl+C and Ctrl+V the shapes from the Gradient parts, I changed the colours (no gradient colouring).

Vector Shading are mostly done with pen tool. I had to dragged each anchors and handles to adjust its shape so that it looks compatible with its counterpart.

Colour are mostly the same shading from its respective colours (Blue, Red, and Green).