Arabic-----English translation

How can I say 'بخلاف' in English as in this sentence?
.الكتاب صعب بخلاف/بعكس غيره

على فكرة، كان من الممكن تسأل في ال
Misc. thread, it's for both Arabic <-> English.

You could use 'unlike'
This book is difficult, unlike the other.

thanks