The article I referred to from seoroundtable.com says this:
"The related command is triggered when you click on the "similar" link in the search results...When you click that link, it basically triggers an advanced query for related sites. The query is [related:www.seroundtable.com"
(source:
http://www.seroundtable.com/archives/020785.html)
So you are saying it is something different, they are saying it is the same thing. So I thought I would check back on what Google actually says:
"The query related:URL will list web pages that are similar to the web page you specify. For instance, [ related:
www.consumerreports.org ] will list web pages that are similar to the Consumer Reports home page....You can also find similar pages from the “Similar pages” link on Google’s main results page"
(source:
http://www.googleguide.com/advanced_operators.html)
From these two references it is clear to me that they are (or were) the same thing.
You say that a similar: command returns different results to a related: command. Well it would do because there isn't a similar: command! If you do such a search all you will get is results relevant to the site in question and the word "similar". As explained in the two referebces above, "similar" was just a link to the related: command.
In honesty I think you are concerning yourself over nothing.