I am just looking at docker images in https://hub.docker.com/_/node/
For every version, the images are categorized into Alpine, Jessie, Stretch, Buster etc. What's their meaning?
In docker-Context here are the important informations you need.
Alpine
Url: https://alpinelinux.org/
Imagename: alpine
Shorty: Its very small.
Packagemanger: apk
Shells: /bin/sh
Size: Few MBs - current tag needs 2.7MB
Jessie aka Debian 8
Url: https://wiki.debian.org/DebianJessie
Imagename: debian:jessie
Shorty: No LTS anymore
Packagemanager: apt
Shells: /bin/bash
Size: ~50mb
Stretch aka Debian 9
Url: https://wiki.debian.org/DebianStretch
Imagename: debian:stretch
Shorty: LTS is running out
Packagemanager: apt
Shells: /bin/bash and many more
Size: ~40mb
Buster aka Debian 10
Url: https://wiki.debian.org/DebianBuster
Imagename: debian:buster
Shorty: All what you need, but newer
Packagemanager: apt
Shells: /bin/bash and many more
Size: ~50mb
Bullseye aka Debian 11
Url: https://wiki.debian.org/DebianBullseye
Imagename: debian:bullseye
Shorty: Newest debian
Shells: /bin/bash and many more
Size: ~50mb
Ubuntu based on debain
Url: https://hub.docker.com/_/ubuntu
Imagename: ubuntu
Shorty: All what you need
Packagemanager: apt
Shells: /bin/bash and more
Size: ~25mb
Those are the names of the OS in the container in which Node will be running.
Alpine is for Alpine Linux, Jessie and Stretch are versions of Debian. If you scroll down on the documentation link you provided, you'll find a section describing what Alpine is and why you might want to use it.