In Mortal Kombat X, what is the difference between these two "Test your luck" mode?

Firstly, Test Your Luck is a game mode with random modifiers on that affect fight difficulty. These modifiers may either handicap one or both fighters.

Towers follows the normal Tower dynamic. There are 7 fights in total, one after the other, and each fight (i cannot remember if it is each round) will have a system chosen character and different modifiers.

Single player is pretty much the same as the standard single player mode in which you select your character and opponent and when the fight starts (again i cannot remember if this is for every round), the random modifiers are applied.