The XSLT 1.0 stylesheets use Apache Ant to run all stages of generating output from DocBook, whereas the xslTNG stylesheets (following from the XSLT 2.0 stylesheets) uses Gradle to build and package the XSLT and other files that you use, and the xslTNG release that you build or download is run using either Java or Python. Recent releases also include an experimental Docker file so that you can make a Docker image for running the xslTNG stylesheets.