A pension fund tends to mean what your pension is invested in. Remember, the pension is just the outer wrapping, the actual fund might refer to a readymade basket of stocks you can put in that wrapper. While lots of pensions like the state or workplace pensions are still invested in funds, with personal pensions like SIPPs the investment opportunities are much broader. You can invest in stocks, ETFs, REITs, fractional shares and more. A pension scheme or pension plan is the type of savings and investment plan you have set up. So it really refers to the type of account rather than what the money is invested in.