Blogger vs WordPress Blog

re: changing a .wordpress.com site title

The top level domain here is wordpress.com and all sites hosted here on on .wordpress.com sub domains. The site title and the URL of the wordpress.com sub domain do not have to be the same.

1. You can use the theme customizer to change a site title under site identity https://en.support.wordpress.com/customizer/

2. The Site title (blog name) and/or the optional Tagline can be changed on the top of this page at any time. >Dashboard > Settings > General ... "save changes".

http://NAME_OF_BLOG.wordpress.com/wp-admin/options-general.php

* You will have to replace NAME_OF_BLOG withe the actual name of the blog in that URL.

That is exactly where search engine spiders look for the site title and removing it from there can cause issues with getting your content indexed. Note that the site title (blog name) and blog address URL do not have to be the same but it's better for SEO (search engine optimization) if they are the same.