I would say cash games are more about picking your position/table/opponent, while mtt is more of a sitting down and going with what you're given. Both are poker, both are it's own way of grinding towards the top and both have their pros and cons.

Cash games are indeed more difficult overall than tournaments for a number of the reasons already listed above. However, they are definitely worth the challenge because they will make you a better poker player in the end and therefore a better tournament player as well.