Difficult is the opposite of easy. It means that something requires lots of effort to do it. Hard can be the opposite of "soft" (such as a hard pillow and a soft pillow) but it can also mean "difficult."
For example, you can say:
The test was difficult. = The test was hard.
It's difficult to understand the teacher. = It's hard to understand the teacher.
The word hard is a little more informal, so it's better to use difficult in more formal writing.
The word hard can also be an adverb to describe doing an action with great effort or energy. We often use it with the verbs work and try:
The most famous groundhog of all is Punxsutawney Phil, named in honor of his hometown in Pennsylvania where he acts as the spokesperson for all groundhogs Its the only mammal to have its own day named after it and as legend goes, every Feb 2, the groundhog emerges from hibernation If it sees its shadow, six more weeks of winter lie ahead, and if not, spring is on the way.