cant really tell since i never played factorio
i think the biggest difference is that in factorio hostile npcs can ruin your factorio and you have to implement tower defense like system for defense, as far as ive seen from videos
satisfactory has a bigger exploring factor (different biomes on huge map in first person) than factorio as well as a "better" (i prefer it because its fps) fighting mechanic...
You can 100% choose your own pace with satisfactory. wanna build ultimate factory ? do it. wanna build chaos ? no problem. you wanna explore the map ? go ahead, you just might want to research some weapons and efficient forms of transportation first.
And if you are "bored" with one part it doesnt matter when you just turn around and do something else, or leave the game running for an hour