Question

Why it is easy to push lawn roller as compared to pull it?

Answer 1

I think you are mistaken.
It is easy to pull the lawn roller than push it.

The force applied to move a body depends upon the effective force applied on it including its weight. As the effective weight in the case of pulling is less than in the pushing, less force is required in pulling. Hence, it is easier to pull than to push.

In case of pulling, the effective weight of lawn mover = mg-f sin θ

In case of pushing, effective weight = mg+ f sin θ.