Google earlier introduced Hosted Account and Fully Approved AdSense account, and now they have additionally categorized Hosted Accounts, which means a hosted account approved through YouTube can not be used on BlogSpot blogs and vice versa.
You Can not use YouTube Approved AdSense on BlogSpotThis may frustrate many bloggers as it has been handy to easily use an AdSense account through multiple platforms. Now, if you want to use a YouTube-approved AdSense account for BlogSpot, you'll have to upgrade your AdSense account, which means you will have to own a top-level domain (like .com, .net, .org etc) in order to upgrade your account. OR, in case you can not purchase a top-level domain, and want to use AdSense account for BlogSpot blog, you must cancel your existing YouTube-approved Hosted AdSense account and apply for a new account through Blogger.
Google's view on this may have been that fraudulent clicks on blog pages must not have an impact on a publisher's other legitimate media such as YouTube videos that they are already monetizing, so they came up with another category of AdSense account now called 'Hosted AdSense for BlogSpot'.
Since it is one of the most popular and reliable way of making money online, Google is always making it more secure and fraudsters-free so that advertisers and publishers built a right marketing ecosystem.