I can confirm that from those that I know Moderna on average seems to cause much nastier side effects, at least much more noticeable, than Pfizer. Not sure why , whether the vaccines really differ in anything but a fried of mine a young dude in his 20's with good health had some 2 weeks written off from life he was feeling like "dying" , nothing extreme ofcourse but overall very tired and exhausted , headache, fever here and there etc.
I'd say that for those that are unlucky the vaccine side effects feel somewhat like Covid , I had Covid and many whom I know had side effects from vaccines and surely effects are similar only difference is Covid ones are more dangerous , like pneumonia , although on rare occasions vaccine side effects are also dangerous like myocarditis or blood clots.
I think truth be told there is no golden neutral path here, each path has it's own risks and benefits.
Most of the folks I know had Covid in a light way and after a week or so continued on with their daily smoking/drinking/working/sporting whatever, some like me had pneumonia. If I could exchange my case with theirs I would be happy but truth be told our body is so complex and there are so many variables that one can never know before hand. One thing is for sure, lots of fresh air , good sleep and no stress + sporting goes along way.I think one of the main reasons why Covid can attain the death levels it can (which are not that high but could be lower yet) is because we may have a large civilization of around 8 billion but many of those 8 billion are either old or sick or have underlying health conditions and are able to live simply due to the luxuries and ease of modern life (cars, healthcare, drugs, assistance etc)
Even for the bad cases if the body has been in good shape before , a timely and correct treatment in hospital typically gets folks out in 2-4 weeks.