Coop vs Singleplayer

Hi Folks,
atm im playing lords of the fallen with a buddy in coop via Friend's pass.
We are kinda blasting through the game and are not checking every corner of the game.
Im just wondering if i should buy the game right now while it is discounted and replay it solo after some time.
In your opinion what the biggest difference in playing it solo and coop?
Is it way harder as a solo?