Among Website and Blog which is easier to manage and which is more profitable? I have learned that blogs needs to be updated frequently for maintaining high traffic and Pagerank,whereas website needs a one time work.
There is no definite answer to this as either one has a possibility of unlimited income in theory. A blog is simply a type of site and it can certainly make a lot of profit, as can a standard website.
That is wrong. Both blogs and websites may require to be updated frequently ( depending on the niche you are in) At the end of the day, a blog is also a website. Both can earn unlimited income in theory as myp said, but setting up a blog is easier because you have ready made solutions like Wordpress available.