Exynos 7870 was more popular and common soc used in Samsung phones. I believe few model running on 7870 soc came with android 9 pie out of the box (and had treble support) which helped the development of older phones running on same chipset. On the other hand Exynos 7880 was only used in galaxy A5/7 2017 models (same fate for Exynos 7885

). EXYNOS 9611 is the new Exynos 7870

.
List of 7870 phones:
High activity devices:
Galaxy J7

Galaxy J7 2017/Pro--my phone
Galaxy J7 2018 /Star (treble offical)
Galaxy A3 2017
Galaxy A2 Core (treble offical)
Galaxy M10 (treble offical)
Galaxy Tab A 10.1

Galaxy J5 2017
Galaxy A6 2018 (treble offical)
Galaxy J6 2018 (treble offical)
Galaxy J7 Prime

Galaxy J7 Prime 2
Galaxy On6 (treble offical)
Galaxy On7

Galaxy On7 Prime

Galaxy Tab Active 2 8.0"
Galaxy J7 Nxt
Galaxy J7 Core
Galaxy J7 Neo
Low activity devices:
Galaxy Wide 3
Samsung Galaxy Tab Advanced2
Samsung Galaxy On Nxt
Samsung Galaxy Feel (SC-04J)
Samsung Galaxy Halo (J727AZ)
I swear that you do not know the last 2 devices.