Are free MMORPGs any more difficult compared to paid MMORPGs?

Hmm, that's a tough question. I would say it depends on the game, but I can say every free to play game maker companies need money to survive in the market. So even if the game is free, the high possibility there will be in-game payments such as cosmetics and boosts.

 

I don't think price determines difficulty at all, especially since MMORPGs have different purposes from each other for different reasons. Some MMORPGs are more social than others, some are more about exploration and discovery than others, some are about completing tasks/missions/quests than others, some are about defeating hard bosses than other; it all depends, especially what the primary focus is on. I usually think price determines content and quality than difficulty.