This year was my first year ever experiencing benzos. I went a few months where I experimented pretty continuously with Ativan and Xanax, to the point where I had pretty nasty withdrawls. Coming from a clean slate and being benzo niave, I'll tell you my conclusions after those few months:
Ativan and Xanax feel quite different, for me they were not really comparable. I started taking Ativan, usually 1mg to 2mg. For me, it was like a subtle relaxation would overtake me over the course of an hour. It was almost as if I wouldn't realize it until it was already there. I would try to move and realize my limbs were heavy and I was feeling very content and comfortable. Laying down and reading felt immensely enjoyable because I just didn't have a care in the world.
Then I was given Alprazolam (Xanax brand name). I took 1mg of that and it felt totally different. Within half an hour I could tell I was getting fucked up. My coordination dramatically worsened and I didn't feel so much sedated as just disinhibited and carefree. All my muscles felt heavy and relaxed, but my mind was not as relaxed as on Ativan. In fact, I was somewhat productive on these doses of Xanax. I took 3mg on night, and I forget everything I did that night. I turns out I had installed a new computer game and played it for an hour, and I have almost no memory of that.
So my take: Ativan is good for relaxation/anxiet. Xanax is good to totally take a mind vacation.