Explore the pros and cons of having both a 401(k) and IRA for retirement planning. Learn why you might choose a Roth 401(k) over a traditional one and compare Roth IRA vs 401(k) to find the best investment for you. Discover how to maximize profits and become a millionaire with the right retirement strategy. Get the inside scoop on your money with WSJ's Your Money Briefing and NerdWallet's expert advice.