A direct rollover to a Roth IRA is one paid directly from the 401(k) plan to the Roth IRA for your benefit. If the payment is instead made payable to you and you subsequently roll the distribution over to a an IRA (traditional or Roth) within 60 days, it's an indirect rollover.
A direct rollover from a traditional 401(k) to a Roth IRA should have code G in box 7 and the taxable amount in box 2a. If you had no after-tax contributions in the traditional 401(k), the amount in box 2a will be the same as the amount in box, 1. With a direct rollover, one would usually roll over the entire distribution and have no taxes withheld shown in box 4. With the entire taxable amount rolled over, estimated taxes may have to be paid to avoid a tax underpayment penalty.
