Traditional IRA has higher contribution limits. You can contribute pretax money up to 18k on it. Since the government doesn't tax it upfront, you start paying tax when you start using it.
For Roth, it is 5.5 k a year max contribution a year on a after tax money. Taxwise you only pay tax on the gains but not on your principals.
If your company offers traditional go with it. You may get employer match also so free money.