This is a question we frequently get when meeting with Chevron employees. The answer is fairly simple, yet the implications of misunderstanding the difference could cost a retiree thousands in taxes at retirement.
Chevron Common shares
The Chevron Common shares you hold in your Chevron Employee Savings Investment Plan (ESIP) (better known as 401(k)) are shares you purchased over time with your own ESIP contributions or cash from matching contributions.
The ESOP shares are a different story. In December 1989, Chevron formed an Employee Stock Ownership Plan (ESOP) and borrowed $1 billion to purchase shares of Chevron stock. As the loan was paid off, shares were released from the ESOP and deposited into the 401(k) as employee matching contributions. This continued until October 2013 when the ESOP ran out of shares. Chevron then went back to making matching contributions in cash.