From the Turnitin website: 'There is a very distinct difference between what Turnitin flags as matching text (aka: similarity index) and plagiarism. Turnitin will highlight ANY matching material in a paper—even if it is properly quoted and cited. Just because it appears as unoriginal does not mean it is plagiarized; it just means that the material matches something in the Turnitin databases'. Plagiarism is all that matters. As long as matching text is properly quoted and cited it is fine.
Plgiarisma means stealing ideas of others by incorporating in one's work but with no citation . I agree with Donal O'Keeffe that matching similarities do not mean plagiarism if they have been properly cited.He also suggested a database from which we can get help, namely Turnitin databases.His advice will be useful for researchers.I recommend it.
In a narrow or micro sense textual similarity and plagiarism are two different things where textual similarity is detected through anti-plagiarism tool but plagiarism not easy to detect by using this tool because thought of other person may be alter by cleverly writing and paraphrasing the original work without change of meaning.