First of all, their algorithm is different from the database. Because of the difference of algorithm and database, the duplicate checking results of the two systems may be different. Generally speaking, the duplicate checking result of paperyy may be higher than that of HowNet, because the duplicate checking standard of paperyy is stricter.
Secondly, their scope of application is also different. Paperyy is mainly suitable for duplicate checking of first draft and revised draft, and can detect most plagiarism. HowNet is the most widely used duplicate checking system in universities and periodicals, which is suitable for duplicate checking of final drafts.
In addition, their charging standards are different. Paperyy charges are relatively low, while HowNet charges are relatively high.
Different duplicate checking systems have different algorithms and databases, so the results of duplicate checking will be different. Therefore, it is suggested that you can use regular free duplicate checking software such as paperfree, papertime, paperYY to make corrections, and finally use the testing system consistent with the school for final inspection.