J-1 Student Tax Filing Question (Worked 2 Summers)

Hello,

I worked in the U.S. twice as a J-1 student, each time for about 2 and a half months (last summer and this summer). I haven’t filed taxes for either year yet, and I’m wondering:

  1. Will there be any penalty or fee for not filing last year’s return yet?

  2. I’m confused because when I uploaded my W-2 form to another agency’s tool, it said I owe about $150. But when I tried to do my taxes with TurboTax, it showed that I should get around a $200 refund.

Why could there be such a big difference, and what should I do to make sure I’m filing correctly as a non-resident?

Thank you!