i you picked interesting subjects for both pics
i agree the second shot looks underexposed
and i think both shots lack clarity. the spider could be really cool but the details are lost.
you could really boost the dramatic effect if you played with the 2nd photo in some post processing software.
Its new to photography so take my comments with a bucket of salt but it looks like you might have tried a flash on that spider, or had a bright backlight. If it was a flash, i'd have tried a bit longer exposure and no flash or blocked the backlight. The details to me seem lost. When your photographing spiders, feel free to experiment. They love to hold still for ya... heres one I took at night, so I had to use flash. Its got a bit of the same problem, and I don't think I had it completely in focus, night and all. But I wanted to show the same kind of detail problem from a flash.
And for the record, thats one CREEPY looking thing... I love photographing spiders for macro & editing practice but hate looking at the freaking things lol.