Ghulam Yaseen Shar:
Thanks David for your response, but there is difference between size of both directories and liferay-ce-portal-src-7.2.0-ga1-20190531153709761.zip does not contain any *.properties either *.xml files which are required while building liferay portal from Source code.
Reference blog: https://liferay.dev/blogs/-/blogs/getting-started-with-building-liferay-from-source
It looks like the zip file is automatically generated by github, thus outside of Liferay's control. The blog article you link mentions cloning the full repo (and that it takes time). If you want to save that time, I'd recommend to not use github's zipfile, but the one distributed by Liferay (e.g. on sourceforge).
However, for maintainability it's best to not build from source, but run with the distributed version and implement any changes in plugins. Often, when people want to build from source, they're not developing on Liferay itself, but implement custom modifications. And that is a recipe for disaster - go the plugin route. If you indeed want to develop the core and contribute back, then this warning is for others who come along and see this post later.
(Attribution: The basic info (source zip generated) for this answer came from my colleague Charles Austin)
