Both BA and BA (hons) are three-year courses. The main difference is that in BA you study a wide variety of subjects with a greater knowledge of any one subject. Eg: you have 3 ancillary subjects in first and second year but have to choose one of those in third year or get a double or triple major (depends on what the college offers).
In BA (hons) you specialize in one subject only and have to do an in-depth study of that subject. Eg: In BA (hons) Psychology you study psychology in all three years of graduation. An honours degree is usually considered better for academic study while simple BA provides a more rounded development and knowledge of various subjects.