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:
Thomas Burberry was born in 1835 in Brockham Green, Surrey. Burberry opened his own small clothing outfitters in Basingstoke in 1857. At that time Basingstoke was a small country town. Nowadays, the Burberry Group is a leading global fashion brand which now sells womenswear, menswear, nonapparel and childrens wear. It is famous for its iconic trademarked check design and British heritage branding.