The meanings are similar.
I would say that the slight difference lies in how realistic the subject of a person's desire is...
For example, a person that "hopes to be able to speak English one day," may feel that they may one day be able to achieve their aim or goal.. but if a person says that they "wish that they could speak English fluently one day," then this implies that their goal is either very far off or that they might never be able to achieve it.
But that is just my personal opinion as to how these words are used. I don't think you will find an explanation like this written down anywhere.