I think it’s just preference. Apologia is more wordy, lots of info on a page, -requiring a slower digestion (mentally-speaking); AIG is much less wordy, but also less conversational (and less interesting), IMO.
We tried AIG, but we were bored and they weren’t interested in listening to the readings.
Whereas Apologia, my son has always enjoyed (except the plant one), doing it himself; he’s learned so much. He still brings out different volumes to re-read under certain circumstances. For my dd, it was too wordy; so she uses living books and the Wonders of Creation series from Masterbooks, w/the free study guides. I think I’m going to try the Apologia Anatomy with her using the notebook, though. We’ll see…
However, others prefer the AIG over the Apologia.
Either is good, it’s just a preference issue.
Don’t know if I was helpful or not!