Generally speaking, VIP academic journals have a wide coverage and strict testing. Paperask is more flexible, and its detection algorithm is somewhat different from VIP, which is relatively loose. For the first draft and the middle draft, you can also use the paper series such as paperfree and papertime to check the duplicate websites for free. If you finish your paper, you should check it with the duplicate checking system required by the school or periodical.
Generally speaking, which is stricter, Paperask or VIP, needs to compare their duplicate checking principle, database, algorithm and so on. At the same time, according to the specific situation, such as what kind of duplicate checking system is used in the school, choose the appropriate duplicate checking software for testing.