What Kobo Writing Life actually pays you for one sale — from Kobo's own published rate card, not from a number someone copied off a blog.
It multiplies a published rate by a price you type. It does not know how many copies you actually sold, how many you gave away, or how much you spent on ads to sell them.
TrueRoyalties reads your Kobo statements and your free downloads, puts them next to your KDP royalties and your ad spend, and shows the profit that is left — book by book.