How different is "to do so" from "to do that"? Are these expressions interchangeables?
For example:

Before we do so, we have one more paragraph to review.

Before we do that, we have one more paragraph to review.

Do both sentences mean the same?

Question

How different is "to do so" from "to do that"? Are these expressions interchangeables?
For example:

Before we do so, we have one more paragraph to review.

Before we do that, we have one more paragraph to review.

Do both sentences mean the same?

Answer

Yes, interchangeable. Another example:
"We could go to the beach."
"Yes, let's do so." / "Yes, let's do that."

Answer

In this context, they mean the same.

Answer

And just to add 'my two penn'orth'  (which is the British equivalent of two cents' worth) ... it is once again a question of formality. The two mean essentially the same, but the 'so' expression is somewhat more formal and 'educated' in tone.