Liferay internally uses spring and hibernate. In that perspective, I want to ask that is it correct to say that Liferay is built on top of Spring and hibernate. Please correct me if I am wrong...thanx in advance.
If you also use in a context where you assume that it is not exclusively built on top of those frameworks, you will be correct.
Hibernate and Sprint are 2 pillars of several that sustain Liferay. Hibernate for instance is essential for developers using Liferay as well, even if they do not know or do not care about how the service builder does its job.
Liferay 7 is a bit different as we are seeing OSGi becoming more and more important, and significantly more utilized for building custom modules and sometimes replacing spring functionality.
Overall, it depends on your context and angle. Struts, Spring, Hibernate, OSGi are all mixed in harmony with Apache libraries, scribe and other famous libraries to build Liferay. And this is just with regards to back-end stuff.