Digital OPK vs regular OPK: which is more accurate for ovulation?

I am asking for my friend I was told the digital are more accurate but she said her period was may 5 may 9 she said she tested cd 7 with a digital and got just a circle and she then tested the next day got a full blown smiley face and she said she got it on cd 8 and now she’s currently on cd 9 she also took a opk and it didn’t say what the digital is showing she said that she was at her doctor this past Monday and she was experiencing some cramping and she told her Obgyn and she said that it’s probably ovulation… she said she has pcos been trying for a baby now for about couple months now since her miscarriage and had a chemical pregnancy in Oct