There is a dramatic difference in the quality of the enthuware and WhizLabs mock tests, with enthuware easily being the superior product. Yet WhizLabs charges significantly more money.
In addition to the points made by the previous posters, I'd like to add these issues with theWhizLabs OCAP and OCJP mock exams:
The mechanism for reporting problems: With WhizLabs, if you want to report a problem with a question or explanation, you have to send an email. With enthuware, you submit your question to the forum so others can learn from both your question and the response (just like JavaRanch). Questions are marked to indicate that there are comments in the forum so you know when to look for them.Response to questions: WithWhizLabs, I have yet to receive a response to any of my emails about the test questions or explanations. With enthuware, I've received a response in the forum within 24 hours.Appearance: With WhizLabs, the window in which the questions are displayed is a fixed size and is small enough to frequently require scrolling. With enthuware, you can adjust the size of the window and the overall appearance is very much like the real exam.Code snippets in the questions: With WhizLabs, about a third of the questions have every line of the code snippet beginning in column one. It is incredibly frustrating and a waste of time trying to read code like that when you want to be focusing on the intent of the question. You don't see that with the enthuware product.Reviewing results: With WhizLabs, you can view each individual question in order of their appearance or view them all on one page. With enthuware, you get a summary screen where you can sort the questions by topic, by pass/fail, or by questions that you marked. You can also cherry pick the questions you're interested in reviewing without having to view them sequentially.
I believe enthuware is also developed in India, but there are very few grammar errors and they are minor. Overall the product is well thought out and designed. Their explanations for test answers are actually useful and worth reading, plus they throw in addition information or examples where warranted. The product is ridiculously cheap for its value.
WhizLabs needs to improve their product on so many levels and their lack of response to their customers does not bode well.