Hmmm, some very interesting points here, however, nearly all games, including both of these, follow one rule of thumb...
Any and all things are weightless when stuffed in your pocket. With that said, Terrarians can defeat these huge monsters with huge weapons, but let's not forget Steve can kill massive monsters with pretty weak equipment(even all Diamond gear isn't so powerful) that CAN break, not to mention no health extensions!
Steve may still be stronger.
Oh, and Steve can swim up waterfalls.
Now I may have overdescribed Steve and barely described Terrarians.
Now, Terrarians rely on much more powerful equipment, but they also go up against much worse enemies! And Terrarians really can vary much more in strength, depending on what KIND of equipment they use.
I honestly think this concept has a ton of possible ways to look at it, so it's hard to say honestly...