Well, more frames rendered -> higher frames per second, but the real kicker is analyzing frametimes themselves:
One of the primary reasons for measuring frametimes was AMD's pretty horrendous Crossfire implementation up to the HD6000-series when compared to Nvidia's SLI. Here, you were getting more frames by using two or more AMD cards, however frametimes were so erratic, ranging from high to low, that a single card could many times provide an experience that was as good or even better than Crossfire.
To measure this, frametime graphs as well as percentiles, which are represented as the number of frames that take longer than a particular monitor refresh interval (60Hz -> 16.6ms, 120Hz -> 8.3ms, etc.). TechReport and other reviewers use frametime analysis to show how 'smooth' performance is, and this perspective is more useful than talking about framerates.
Canon 6D|24-105/4L |70-300/4-5.6 IS USM|50/1.4 USM|50/2.5 CM|50/1.8 STM|85/1.8 USM|Samyang/Bower 14/2.8|24/2.8 IS|Sigma 150-600 | C
Canon EOS-M|11-22 IS|22/2|EF-M 18-55