Flo and Glow apps showing different ovulation days!

I am confused as to why the flo app and <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> would predict my ovulation a week apart.

I think the flo app was accurate. I had fertile discharge around that time and sore nipples. Nipples have been sore ever since which is normal for me.

Thankfully we were able to baby dance around both predicted days.

Dose anyone else use both apps? Do you have the same issue as me?