I have been working on two websites for the past couple of years. I used same links for link building for both the websites but since May 2013. No signs of being hit by penguin one of the two websites keywords are drastically falling where as the other one is stable. what might be the reason.
Depends how long the piece of string is one uses to measure things! Seriously though how can anyone answer that question other than with sheer quess work? So saying that > It might because one domain is better named than the other More "guesses" will/may follow....
Of Course there are several reasons for that one it might be happens based on the relevancy of the content & Back links Or the visitors flow or the second may lost some of your quality you build from past like this you first check your site may lost those links & the visitors flow then you can understand the solution easily.
Those two sites have different things which are responsible for SEO.. Two sites can't be same in term of SEO.. they have different domain name benefit, content relevancy, age of domain, backlinks parameters etc..