The obvious reason these two are similar is that they are both shoujo-ai. Besides that I found the two manga were similar because they both were about school life, friendship, love, and had cute drawings. They also had the same kind of feel to them. Gokujou Drops is a little more mature, but if you liked one, you'll probably like the other.
Both series is about two girls in love with each other, The plots aren't exactly the same but if you like one of them you should like both.