I want to ask you that can we define different title in different pages or different post of the blog on blogger.com Like we do in normal website.
I think yes you can. While writing the contents of a post/page there is a field to provide the Title as well.
There is nothing like think......Yes you can surely use New titles and post for your blog....See example : lovehurtsstillwant dot blogspot dot com
of course, you can modify page title/post title and can use it directly on <title> using if statement
I think you can use custom metas for that or better yet a custom widget to support that Title Tag structures.
You can do it, change the your <title></title> tag into <b:if cond='data:blog.pageType == "index"'> <title>YOUR BLOG NAME</title> <b:else/> <title><data:blog.pageName/> | YOUR BLOG NAME</title> </b:if>