Practice manual and compilation

In each chapter of Practice Manual, the summary of the topic is given at the beginning and you will find that the initial questions cover basic concepts of the topic and become progressively advanced with each question, although this may not be true for all the subjects. Practice manual also includes past years' questions. 

The difference with Compilation is that compilation only covers past years' questions topic-wise and states the attempt in which each question was asked.  

So, there is overlap of some questions between the two.

From a revision point of view, Practice Manual is more helpful.