They both have their strengths and weaknesses. I'll boil out the similarities for you:
Biology: More information to remember than Chemistry. In this sense, it is easier as you need to learn facts and there will be fewer skills to hone and practice (principle - you know it, you know it)
Chemistry: The amount of knowledge required is less and what you learn you apply more by using skills and techniques picked up during the course. Therefore, more logic is required. Could be considered easier as you have to know less and work things out in the exam)