This is a perfect example of the difference between hard and soft lighting. In fact your hard lighting is incredibly hard and your soft lighting is very soft. I think both capture the essence of this assignment very well. Great job.
The composition of the butterfly photograph is stunningly beautiful. It’s very well organized, it abides by the rule of thirds, it’s simplified from both and object and color standpoint and you’ve used a perfect depth of field to isolate your main object.
My only criticism is that there is a small bit of amputation at the top from of the photograph. You’ve cut off the smallest piece of a flower petal and that looks fairly distracting. But the other sides of the photograph are well done. The top amputation just looks a bit accidental. Its small mistakes like this that draws your viewers out of the picture because they are subconsciously distracted by these small details.
Secondly, your butterfly isn’t in perfect focus. This could be because of 1 of 2 things. Firstly, it could be because you experienced slight camera shake, or secondly it could be because you didn’t have the depth of field set properly to capture your main object. In either case it’s avoidable.
Again, although you can barely tell it’s not perfectly in focus when the image is in small format, as soon as you blow it up the loss in detail and crispness acts as a slight distraction.
You are defiantly on the right track though. I think if you can clean up these small details you’ll have some very professional looking photographs in your portfolio!