One lens has more grain than the other

Hey guys so I have been noticing something for about 2 months now while doing sports photography and overall just photography. One of my lenses 100-400 f4.5 is like always really grainy and has more noise and always like not sharp compared to my other lense 55mm f1.8. I don’t know if it’s the photo viewer on my computer but the lense always adds grain and it shows up on the pc. This used to not happen on my 5d mark iii the lense used to be completely fine. Now with my r10 it did decent in its first 2 sessions then when I switched to raw it just adds so much great my photos compared to my 55mm f1.8 Anybody know what I should do or suggestions?