I understand that the following book is about the basics of probability:
But I don't understand the difference between the following two books. What is the difference between the intention of these two books?
Probability, Random Variables, and Random Processes by Hwei Hsu:
Probability & Statistics by Spiegel, Schiller, Sri Nivasan:
The first two seem to be on probability while the third claims to contain some statistics. The first book on probability theory seems more basic than the second one (for example, it does not claim to cover Random Processes), but this is best checked.
The first book is probably more basic and may spend more time on basic probability concepts. If you look it up in an online store, your may be able to view the index.
The second book (Probability, Random Variables, and Random Processes) covers probability and random variables (including multivariable) in half of the book (200 pages or so) and then it moves onto Random Processes (for around 100 pages). It deals with Estimation Theory (Maximum Likelihood among them) briefly and then it covers Decision, Queueing and Information Theory (one per chapter, in the remaining three chapters). This book therefore covers probability in a reasonably rigorous and detailed way (At least as much as a Schaum book can) and important applications.
The third book, judging from the the cover page, is less detailed than the second, and covers statistics mainly (as it intended audience seems to be a business student).