Yes, there are different degrees of CFS, and many different (but related) symptoms, all a result of systemwide inflammation and low cellular ATP, including in the muscles and brain.
Main common CFS symptom is the inability to get a good night's sleep and wake up refreshed. Another is exercise making them feel tired and achy all over for 2-3 days, much like the flu, instead of energizing them.
Otherwise, CFS varies person to person, and goes by many different names due to this variability, and according to what type of doctor diagnosed it.
A common and recognizable mild case of CFS in women 40+ is also known as 'Menopause Symptoms', in men it is called 'Night Sweats', since CFS (low ATP) starves the energy-hungry hypothalmus in the brain, thus affecting temperature regulation, sleep, and hormone levels.
Someone who has had chemo run down their immune sustem calls CFS 'Chemo Fog'.
There is a 0-10 CFS Energy Scale that elaborates on the different degrees of CFS. Google it to get the details. Briefly:
0 = bedridden
1= 'up' 1 hr/day (Up= in a chair)
4= unable to make it thru an 8 hr workday
5=barely make it thru a workday
10= normal work, play, sleep.
By definition, for CFS the various symptoms continue for 6+ months, though they will vary in severity during that time.
I retired from work so I could rest more. At the time I didnt know why I was so tired all the time; All my medical tests were normal.
After a lumpectomy (which healed up in weeks), for months I could only sleep 3.5 hrs/nt, was too tired to get out of bed, except for using the bathroom. I had too much brain fog to read.
After googling Brain Fog & Fatigue, I learned about CFS.
I was a Energy level 4 when I left my job, and a 1 for months after my surgery.
Eventually I progressed to also going to Church (1 hr) on Sundays, which would be Energy Level 2 (up 2 hrs total).
I started bicycling twice a week. Just to the nearby park at first, but kept adding a little more each week. It would put me in bed for 2-3 days recovery each time, but I had nothing better to do with my time. The house stayed a mess.
Two years later, after a setback from a Flu shot, I am (once again) a Energy Level 4, and can bike 30 miles 3x/wk.
Recovery is slow. But possible. The body can heal itself if it has the right nutrient ' tools'.
Rebuilding the immune system and eliminating stressors is the key.
So is education, so you know when your doctor is clueless about the underlying cause (i.e. a virus, which may or may not show up in a test, depending on the Lab) and cure (BUILD the immune system!).
Side effect is that the cure for CFS is also the preventative for Cancer. :-)