What is the difference between impact factors and quartile scores from JCR and Scimago?

Both organizations calculate a journal ranking and a quartile score, but in a slightly different way and using a different source. The rankings are not directly comparable.

The “Impact Factors” en “Quartile” of JCR (www.jcr.clarivate.com) is calculated by Clarivate using Web of Science Core Collection as the source.

Scimago (https://www.scimagojr.com/journalrank.php) calculates “Scimage Journal Rank” (SJR) and “Quartile” using Scopus (Elsevier) as the source.