A man is painting letters using a stencil onto a round stand-up sign that is lying sideways.
A guy works on a sign by putting letters on its round surface while it's on the ground.
Just because a man is painting a stand-up sign that is laying sideways does not mean that the sign is on the ground.
Just because a man is putting letters on a stand-up sign does not mean it is while it's on the ground.
The guy may be paintin on a sign lying sideways on any flat surface and not necessarily on the ground