Who’s Classifying Trails?

I find it perplexing when I go to a Park’s website to check out the available trails, their website lists the trail as a “Difficult” hike, I then go to a hiker website such as “All Trails” and the same hike is listed as “Easy”? I guess it is all relative to the individual hiker’s ability who is posting. I decided to make the 2 hour drive and hike the trail, ironically in my opinion, neither was accurate, it was a “moderate” hike. Would love some feedback on how each hike difficulty level is determined!