Hi Mahima,
Both the colleges are one of the best colleges but both differ in ranking.
St. Xavier's Mumbai was established in the year in 1869, but despite being so old it ranks far behind St. Xavier's Kolkata which was established in the year 2017 but ranks 7th in the National Institutional Ranking Framework in 2020.
You should also check out the following link for further comparisons on various basis: https://www.careers360.com/compare-colleges?college=1879-5814-course=0-0
HOPE THIS HELPS
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