Why are certain items of income, gain, deduction, or loss separately stated on a partnership or an

Question:

Why are certain items of income, gain, deduction, or loss separately stated on a or an S tax return?
Corporation
A Corporation is a legal form of business that is separate from its owner. In other words, a corporation is a business or organization formed by a group of people, and its right and liabilities separate from those of the individuals involved. It may... Partnership
A legal form of business operation between two or more individuals who share management and profits. A Written agreement between two or more individuals who join as partners to form and carry on a for-profit business. Among other things, it states...