The main difference between the traditional and Roth 401(k) is that with the pre-tax option, you pay the tax on your contributions and the earnings when you withdraw them at retirement at that current tax bracket, whereas with the Roth, you pay the tax on your contributions upfront, but the earnings can be withdrawn tax free.

Depending on how your workplace 401(k) is set up, your employer can match a certain percentage of your 401(k) contribution. Think about it as free money! This is a great benefit employers often provide to allow you to build up your retirement savings.  

While both an IRA and a 401(k) are retirement vehicles, a 401(k) is an employer-sponsored retirement account whereas an IRA does not involve your employer but still allows you to contribute towards retirement. Be sure to look into the contribution limits of each.