Asset allocation decides what you own. Asset location decides how much of it you actually keep after the IRS takes its cut.
Two people hold the same $200,000 portfolio: 60% total stock market, 40% corporate bonds. One keeps the bonds in a 401(k) and the stocks in a taxable brokerage. The other does exactly the reverse. Same funds, same gross returns, and a different amount of money at the end — potentially tens of thousands over two decades. Nothing separates them except which account held what.
— Educational, not financial advice.