What is the difference playing against human vs chess engine? I have been playing with chess engines for over a year now at extreme difficulty levels. I never played a single game with a human player. I am worried that when i face humans in a tournament, my chess thinking must be completely different and i might not survive.

Does playing against chess engines improve your ability better than against human players? What do you think?
There are two separate problems with your trainingspartner: Strength and style.


Generally you improve the most if you play against opponents slightly stronger than you. You have to adapt by upping your game, but you are still able to adapt! If you are always crushed you only learn to be solid at all costs. You can see this a lot if teenage prodigies play too early against world class opposition: Their game dries out. They systematically unlearn all creative impulses, because every risk taking is punished. 
If you play against engines that always beat you, their style doesn't really matter. But if you would play against an engine only slightly stronger than you (which would be a better choice), you would experience the problem, that you adapt to their particular style. Which usually means you get very good at sniffing out tactical pitfalls, but your positional understanding will stay underdeveloped. I know this very well because I played for two years almost daily against a Mephisto board computer before I joined a chess club and it took me many years to stop losing against human opponents who were far weaker tactically.