Treble devices not same as A/B devices and vice-versa. Why?

This XDA blog [How A/B Partitions and Seamless Updates Affect Custom Development on XDA](https://www.xda-developers.com/how-a-b-partitions-and-seamless-updates-affect-custom-development-on-xda/) has some Q&A's, of which : > * My device supports A/B partitions, does that mean I can make use of a Project Treble Generic System Image? > > Not necessarily. Project Treble and A/B support are unrelated. The **Motorola Moto Z2 Force doesn’t support Project Treble, yet it supports the A/B partition scheme**. > > * My device supports Project Treble, does that mean I have an A/B partition scheme? > > This is not always the case. The Honor 9 Lite is a prime example as it **supports Project Treble yet does not have an A/B partition scheme**. (Emphasis added) I thought Treble and A/B devices are synonymous in the sense having one implied other. That's not the case **Why is this? What are the differences?**