<human>:  What is the difference between a 401k and a Roth IRA?
<bot>: The main difference between a 401k and a Roth IRA is that contributions to a 401k are made pre-tax, while contributions to a Roth IRA are made with after-tax money, meaning that you pay the taxes upfront. With a 401k, you don't pay taxes on your contributions until you withdraw the money in retirement, while a Roth IRA requires you to pay taxes on the contributions when you make them, but you won't need to pay any additional taxes when you take the money out in retirement. Additionally, 401k plans are typically offered by employers, meaning there is often a limit on the amount you can contribute, while Roth IRAs have an annual contribution limit set by the federal government.