I am in the military and have a TSP account or a Thrift Savings Account and I contribute to my ROTH TSP. Is that the same as contributing to a ROTH IRA?

[PaulaM]

They aren't the same thing but do function similarly. With a Roth TSP, you can contribute far more than a Roth IRA. For 2018, you can contribute $18,500 in the Roth TSP,  vs  $5,500 ($6,500 if over 50) for the Roth IRA.

https://themilitarywallet.com/thrift-savings-plan-contribution-limits/

https://www.tsp.gov/PlanParticipation/EligibilityAndContributions/TaxTreatment/index.html

[dmertz]

Do not enter your Roth TSP contributions anywhere but in box 12 of TurboTax's W-2 form.  Do NOT enter them as Roth IRA contributions.  Your Roth TSP contributions for the year will be shown with code W in box 12 of your W-2.