Difficult - Doing an action can be difficult. For example, running a marathon and learning a language. Examples: Learning Russian is difficult. Learning to swim is difficult. Hard - can mean the same as difficult. But hard is also the opposite to 'soft'. For example, wood is hard. A person can be 'hard' as in 'tough'. Hard has a more varied meaning. You can also look hard as in trying to see something you can't see easily. Examples: That man looks hard. She looked hard at the sign in the distance. Concrete is really hard. I hope this helps.

The word 'difficult' can always be twitched for 'hard' in any phrase. The work is difficult/the work in hard. Both correct The question is difficult/the question is hard. Both correct However the word 'hard' can not always be twitched for difficult. It can also describe a level of effort or the texture of something. He worked hard all day. Only option The rock is hard. Only option

Hard is a synonym for difficult. They have the same meaning though difficult is used more often in an academic setting.

hard is also used for intoxicating things. for example-> Vodka is very hard.