Pretty hard. But there is a certain difference between them. "専攻(Major or Speciality)" means to literally intensively learn a certain specific field whereas "専門" means not only the same thing as the former but also engaging in something specific. Let's say you are an electronic worker. Then you are in charge of fixing something electronic. That is basically what "専門" means. Like I said, it also means something academic as well as "専攻". I hope my question helps :)