Bear in mind that some differences will be between first and succeeding pregnancies and some will be twin vs. singleton.
My first pregnancy (singleton) was pretty good. I did have morning sickness (never severe, but uncontrolled and a pain), but other than that, it went well (mild heartburn). DS1 arrived at 40 w 4 days. The delivery took forever and narrowly avoided a C-section.
My second pregnancy (singleton) was better. I'd begun to understand what triggered or helped prevent my morning sickness, so it was much more controlled (basically, if I got hungry, I'd feel sick, so I'd eat something at the first signs of hunger). I had mild heartburn with him too. DS2 was 11 days overdue, but I never felt uncomfortable before he arrived. His birth was mostly natural (doctor induced, but I was allowed to walk around and such) and went much better, much faster.
My third pregnancy (twins) was probably my shortest (unsure of dates, but I believe it was 38.5 weeks), however, I was much more impatient for it to end.
Knowing how to control my morning sickness, I was surprised at how much food it took to control it (I didn't know it was twins until 27 weeks). The last trimester was really the worst (I hesitate to use that word, since the pregnancy was still good). It was hard to eat as much protein as I needed without feeling stuffed or having heartburn. It was very tiring to get up and get around (which was necessary with my older boys). In the last couple of weeks, I developed a hemorrhoid, which was really painful. I was so ready for those girls to arrive! The delivery was my easiest and fastest (a homebirth).
All in all, I'd say my twin pregnancy was harder, but not twice as hard. However, in many respects you'll probably find your second pregnancy easier, but in some harder (mainly, having to deal with the children while dealing with the pregnancy stuff).