jQuery Migrate is the more common of the two in our index: it runs on 6,383 websites against 17 for Locomotive Scroll, and 4 sites use both. Counts come from real scans, not vendor claims.
Query Migrate is a javascript library that allows you to preserve the compatibility of your jQuery code developed for versions of jQuery older than 1.9.
Locomotive Scroll is an opinionated JavaScript library that provides smooth scrolling animations and advanced scroll interactions for web applications.
4 sites run both jQuery Migrate and Locomotive Scroll. That is 24% of the sites using Locomotive Scroll, the smaller of the two.
Want to know which one a particular site uses? Look it up and see its whole stack, or compare two sites side by side.