In the given passage, a cup of strong and weak coffee is compared based on their effect and caffeine content. And in the two sentences, even though it is a comparison transition between a strong and weak coffee, the transition word used is "similar".
In both the sentences, the physical effects of coffee are compared, with the same result- <em>"80 milligrams of caffeine or enough to boost a heart rate and blood pressure." </em>This means that both a weak and strong cup of coffee have the same physical impact on a person.
Thus, the comparison transition used is "similar".