I'm about about 3 weeks away from delivering my 3rd child. All 3 of my pregnancies have had some similarities and some differences. My first trimesters in each were vastly different. My second trimester in all three were pretty similar, although after your first pregnancy, you tend to get more uncomfortable and have more pains because your muscles and ligaments have already been stretched out once and aren't as supportive as they once were. My third trimesters in all three have been pretty similar as well, although I am having more troubles with this one (just in that I'm having to be careful to not over-do it because I get the quick contraction and cramps when I do). I've carried all three children exactly the same, but I know that's not the case for most of my friends. (I also have 3 boys, and often you specifically carry boys and girls differently.) My labors have all been pretty similar (fortunately fairly easy), just shorter than the previous.
I really think that each pregnancy is unique, but your body type is the same, so there will be some similarities as well. You're also creating a person with genes from two different families, so that can play a role with differences as well. In my case, I think my increasing age plays a small role in the differences as well. Not that I'm old, but my body is 5½ years older than it was with my first. Plus with my first I had no kids to chase around all day, with my second I had one kid to chase around all day, and now with my third I have two kids to chase around all day (while pregnant). That alone makes a difference as well.
I know people that have had DRAMATICALLY different pregnancies and even labors too though. One time the would get gestational diabetes, another time they wouldn't. One time they would carry side to side, the other they would carry straight forward. One time they would be sick throughout, the other they were fine past the first trimester. In labor, I've seen several times where one was a difficult one, and one was not. Sometimes babies are similar is size, and sometimes they are not too.
So to answer your question, yes, pregnancies are typically different. There are different degrees of difference, which are all dependent of many factors.
I hope that helps to answer your question! :o)