Strange line change effect

I have a Featherlight 7’ with an InspireCast 3000. The rod is 3-9 lbs and the reel is 6.4 max drag. If I switch from 7 lb mono to 8lb braid it casts slightly shorter distances maybe 10’ less not even. However now I can cast medium narrow spoons. I don’t know why that’s interesting but it is. The mono weighs less so I’d have guessed that leaves more weight available for the spoon but the stronger heavier line can support it better for some reason. It’s good information to have depending on what I’m fishing for.