I am not quite sure why two installer options are offered.
Downloading the full installer (more than 500Mbytes) was a bad choice in my case. It takes a long time to download and a long time to install. When I installed the files and clicked “launch Development Studio” it crashes and gave me an error message which made reference to a configuration log file that highlighted a range of conflict issues. After the 3rd attempt of retrying to install I gave up.
Downloded the light installer version and everthing worked fine.
I noted that with the full installer, the version number of Development Studio was much older (version 1.3) than when installing using the light installer (version installed is Build Version 2.2.1…)
Maybe someone should check the Full Installer option as it appears out of date and maybe it should be deleted to avoid this problem for other new users.