Sakura naturally hits harder. Now Sakura at Sarada's age didn't hit as hard as Sarada.
When Sarada is as old as her mother, Then Sarada will hit harder. She is already far above where Sakura was at her age. Plus she has both the Sharingan and Strength of a Hundred....nice.
Let me put it like this, Sakura was not punching holes in the ground at Sarada's age, so its safe to assume Sarada will be making larger holes in the ground by Sakura's age.
Sakura for obvious reasons, Sarada is inside a cave so it look bigger, while Sakura has bigger terrain, so hers is naturally stronger.
But when Sarada is Sakura's age she'll be known as the "planet splitter"....pffft as if, she'll be able to destroy large meteors but not split the planet obviously, such fanfics are reserved for femme and her followers