How does TT distinguish an ira rollover from a distribution

TT looks at the Distribution Code(s) in Box 7 of your 1099-R.

You can't do a Rollover of an Inherited IRA. only a direct trustee-to-trustee transfer. That doesn't go on your tax return.

As fanfare said, distributions paid to a non-spouse beneficiary and reported on a Form 1099-R are not pemitted to be rolled over.  However, a spouse beneficiary is permitted to roll over a distribution from their deceased spouse's retirement account as long as no part of an RMD is included in the rollover.