The main difference comes down to when you pay taxes. With a Traditional IRA, contributions are often tax-deductible now, and you pay income tax on withdrawals in retirement. With a Roth IRA, you contribute after-tax money now, but qualified withdrawals in retirement are completely tax-free, including all the growth.
A few practical things to weigh: if you expect to be in a lower tax bracket in retirement than you are now, a Traditional IRA can make sense. If you expect your tax bracket to be the same or higher in retirement, or you want more flexibility (Roth contributions, though not earnings, can be withdrawn penalty-free), a Roth often wins. Roth IRAs also have no required minimum distributions during your lifetime, while Traditional IRAs do.
Income limits apply to Roth IRA contributions, so depending on how much you earn, you may only be eligible for one or the other. Many people end up using both over their careers to diversify their tax exposure in retirement.