Led Zeppelin 2

Recently, I've been listening to Led Zeppelin 2 in my class. Despite how great their first album was, I'm a little disappointed in their second album.  While the first album was filled with new stuff and felt more versatile, I thought Led Zeppelin 2 is unoriginal. What I mean by unoriginal is that every song sound the same, each song doesn't have a distinction that makes them pop out, thus making it feel like a 40 minute song than an album. There were moments that I liked the album. The drum solo is, should I say, kickin if you know what I mean. Ba-Dam-CHIK! But the problem is that I don't know what song it's from. My guess that the drum solo is in Moby Dick. Because well, why not?..