Apollo is focused more on sales engagement data as compared to ZoomInfo, based on my hands-on experience, which aligns better with Gong.
Also, with the focus being more on sales engagement, Apollo has some advanced features such as advanced automated sales sequences, which are highly customizable, then, the feature of task prioritization, and the analytics, action-oriented, insights
I also believe that the account scoring by Apollo comes very near to high-confidence level accuracy when aligned with Gong's intelligence, which again is a big advantage.
