Its to do with fan blade material. GE90 fan blades composite so make diffrent noise to metal ones.
I agree.... These GE90 (115 & 110) are damn big engines & their design needs to be respected just as any engine does. As a side note, it is a personal pet dislike seeing pilots disregard the need to confirm stabilized engines prior to pressing the TO/GA switch. Laziness and complacency.