Along with the terminology change, there are the following improvements:
- Text is highlighted as it is read out, similar to Immersion Reading
- Screen sleep is disabled while it is reading
- Reading speed is adjustable from 0.5x to 3.5x in 0.1x increments
- Reading pauses when tapping to highlight text, add notes, view reading options, and resumes where it left off when you tap Play button
Kindle app version is 14.99.100. I do not know which versions of FireOS are compatible with this (I have Fire HD 10 Plus 11th gen and Fire 11 Max).