In the U.S. national accounts, economic activity is represented by two separate, yet equally important aggregates: the expenditure-based estimate (GDP), which is the sum of personal consumption, business investment, the trade balance, and government spending; and the income-based estimate (GDI), which is the sum of wages and benefits, interest, profits, rents, and taxes.
While the two aggregates should be the same, there is often a “statistical discrepancy” between them. Changes in this gap can sometimes lead to contradictory answers to seemingly simple questions such as “is the economy shrinking or growing?” - Klein 2023
BEA National Income and Product Accounts Primer
Detailed NIPA Handbook
BEA: Definition and Introduction to Fixed Assets
Definitions and Introduction to Fixed Assets | U.S. Bureau of Economic Analysis (BEA)