Etihad Guest vs KrisFlyer miles to Europe - why such a difference in points cost?

I’m trying to plan a trip for 2 people to Europe flying business class using a combination of Velocity and Amex points. MEL > LHR - FCO > MEL.

In my research I have found that on the Velocity website Etihad comes to 500k miles and Singapore Airlines to 700k miles.  However when redeeming in their own frequent flyer programs on their respective websites, Singapore Airlines comes to 300k miles (including online booking discount) and Etihad to 550k miles.

I’m a little confused as Etihad becomes more expensive on their own website, however Singapore Airlines is significantly cheaper.

I was under the impression that I would require more points for Singapore Airlines than Etihad, but it seems to be the other way around.

I’m left wondering if I’ve missing something?

You haven’t missed anything! It’s just purely down to the way that each program prices their own redemptions vs those on partners. Velocity partner redemptions are relatively expensive (compared to those on Virgin Australia flights). Krisflyer’s pricing on Singapore Airlines flights is aggressive, and Etihad’s pricing for their flights is not.