There are two words in Korean often translated as "difficult"
힘들어요 and 어려워요
What's the difference!?
힘 means "power/energy" so 힘들어요 means something that takes away your energy. It is difficult because it is draining.
This means difficult as in 'hard to do" For example: You don't speak Korean well so communicating with Koreans is difficult. You're not good at math so this Calculus homework is difficult.
You don't understand the homework so doing it is...어려워요
Having a ton of homework all due on the same day is so... 힘들어요
The difference is subtle, but just think:
Is it draining my energy? Then its 힘들어요^^
And if you're having a hard time remember: