Neither of those are CPU model numbers. Did you mean i7-9700K vs i9-9900K? You are looking at the wrong benchmarks (e.g. single-threaded ones) if you think they are equal.
Blue Iris does benefit from hyper-threading.
Both will handle 1300 MP/s but the i9-9900K would handle it with more CPU to spare for things like Windows Updates, remote viewing, and for when you want to review multiple clips at once using the timeline control.