Good afternoon, Rosa.
(1) Yes, these two words are very confusing.
(2) If you study these two sentences, maybe you can get an idea
of how these two adverbs differ:
(a) Last year, I went to Japan specially to learn the language.
(i) That is the one reason I went.
(b) Last year, I went to Japan, especially to learn the language.
(i) To study the language was my number one reason, but there
were other reasons, too (for example, to view the cherry blossoms,
ride the bullet train, etc.).
Have a nice day!
Student or Learner