It’s always irritated me when people say they have flu when it’s a cold, yes ok a bad bad cold, but not flu.
I had flu as a teenager, 35 years ago now, my dad had to carry me to the loo, my parents ended up employing a nurse to care for me, the doctor called twice a day. It took me weeks to recover. That’s the flu.
I had covid last year, and I was completely knocked off my feet again. I would say there was very little difference between the two.
DH said last week he had the flu, yes he was ill I made him hot lemon and honey, and waited on him whilst he died on the sofa, but when he said he had the flu or maybe covid ( he’s never had either, but he did nurse me with covid ) I laughed, and pointed out that he had got up, had a soak in the bath and is now in the living room watching tv - that’s a cold.
If you have the strength and the breath or even simply care enough to tell someone you have the flu, then that’s a cold, with flu you can barely manage to roll over in bed.