Next.js is the more common of the two in our index: it runs on 4,934 websites against 246 for Tengine, and 19 sites use both. Counts come from real scans, not vendor claims.
Next.js is a React framework for developing single page Javascript applications.
Tengine is a web server which is based on the Nginx HTTP server.
19 sites run both Next.js and Tengine. That is 8% of the sites using Tengine, 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.