Both pensions and 401ks have advisors who charge fees. The Underlying investments are the same things...stocks, bonds, etfs, mutual funds.
With pensions trustees direct the investments. With 401ks the individual does.
But if the market does that badly and defined benefit pensions are underfunded they are vulnerable to being converted, terminated, etc.
From DOL:
http://www.dol.gov/ebsa/publications/wyskapr.html#chapter8Chapter 8: Your Benefit During A Plan Termination Or Company Merger
As noted at the beginning of this booklet, employers are not required to offer a retirement plan and plans can be modified and/or terminated.
What happens when a plan is terminated?
Federal law provides some measures to protect employees who participated in plans that are terminated, both defined benefit and defined contribution. When a plan is terminated, the current employees must become 100 percent vested in their accrued benefits. This means you have a right to all the benefits that you have earned at the time of the plan termination, even benefits in which you were not vested and would have lost if you had left the employer. If there is a partial termination of a plan, (for example, if your employer closes a particular plant or division that results in the end of employment of a substantial percentage of plan participants) the affected employees must be immediately 100 percent vested to the extent the plan is funded.
What if your terminated defined benefit plan does not have enough money to pay the benefits?
The Federal government, through the Pension Benefit Guaranty Corporation (PBGC), insures most private defined benefit plans. For terminated defined benefit plans with insufficient money to pay all of the benefits, the PBGC will guarantee the payment of your vested pension benefits up to the limits set by law. For further information on plan termination guarantees, contact the Pension Benefit Guaranty Corporation toll free at 1.800.400.7242, or visit the Web site.
What happens if a defined contribution plan is terminated?