I have created two similar websites (relating to monetary systems). So far, one appears to be loved by Google and the other hated. I'm struggling to work out why.

This is a mystery to me because both sites were created by me with the same design philosophy, both in pure html. Both are packed to the rafters with references to, and information about, their respective subjects.

One issue I'm worried may be the cause is to do with the location of the sites. I got a web hosting package from hostmonster.com for the successful one, but less liked one is just an "add-on" which sits on a subdirectory of the successful one. I wonder if Google somehow detects this and treats it as a less significant website?

EDIT: Just to clarify, even though one site is an add-on that sits on a subdirectory of the other, the URL is arranged to look like it is a root. I.e. the unpopular site can be accessed directly with a simple www.myunpopularsite.com name, without specifying any subdirectory.