Very simply, in a traditional IRA/401k you put money in pre-tax (you get a tax deduction for the money earned that goes into these accounts), the money is not subject to taxes on earnings while it is in the account, and every dollar you eventually take out is counted as taxable income. In a Roth you put money in after tax, it is not subject to taxes on earnings in the account, and it is not taxed or counted as income when you take the money out of the account. In a taxable account, you put after tax money into the account, any dividends/interest/capital gains are taxed, and when you take money out you only pay taxes on it to the extent you realize capital gains while doing so.
In your tax bracket, you would want to max out the traditional 401ks, since you are paying up on taxes and the deduction is worth a lot. You are not eligible for a Roth, so any additional savings would go into a taxable account. If you put the tax efficient investments (equity index funds) in your taxable account, you will have vanishingly small tax bills from it.