jQuery Migrate is the more common of the two in our index: it runs on 6,682 websites against 3,152 for LazySizes, and 663 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.
LazySizes is a JavaScript library used to delay the loading of images (iframes, scripts, etc) until they come into view.
663 sites run both jQuery Migrate and LazySizes. That is 21% of the sites using LazySizes, 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.