Are some languages more or less difficult to learn than other languages?

It is true that some languages are more or less difficult to learn than other languages because of roots of language. It might be easy for people lived in western to learn Spanish, French, and English. However, it is hard for people in eastern countries to lern those languages. The reason is that languages had been developed from long time ago by influencing each other countries nearby. My father used to tell me that one reason that people value people who can speak English more than people who can speak Japanese is due to difficulty level of acquiring language. There are many similarities in Japanese and Korean: structure of sentence, similar race, influence of history. However, there are more differences between Korean and English: a nuance, existence of a and an, culture difference, and different sentence structure.