Both are tax-advantaged retirement accounts, but they work differently. Here's the beginner-level comparison. Educational only, not financial or tax advice — rules vary and change.
A traditional 401(k) is typically funded with pre-tax money — you get a tax break now and pay tax on withdrawals in retirement. A Roth IRA is funded with after-tax money — no break now, but qualified withdrawals in retirement are generally tax-free.
Many employers match 401(k) contributions up to a limit. That match is an immediate return you can't easily beat — which is why capturing the full match is often the first priority.
A frequently cited approach: contribute enough to the 401(k) to get the full employer match, then consider funding a Roth IRA (more investment choice, tax-free growth), then return to the 401(k) for additional savings. Your situation and tax bracket matter.
Roth tends to appeal if you expect higher taxes later; traditional/pre-tax if you want the deduction now. Many people use a mix. Contribution limits and eligibility rules apply and change over time.
Which account you use matters less than actually contributing consistently and letting compounding work. Confirm current rules or consult a professional for your specifics.