A mobile website is both in design and functionality 100% optimized for use from smartphones and pads. For example, the web site can be viewed very user friendly way, without there being scrolled or not need to be hemmed.
Yes i agree with you that Designed website for mobile not having too much size but also considered that it does not having to much content also because its not worth for user. User generally can not read more information about website they only read required information.
The website developed for mobiles are not more data in it. but it have lot of content. And the management of content is the main object of that website.