facebook vs. twitter

I just never understood the point of twitter when no one can really comment on your status like you can in facebook. I made a twitter account a long time ago because I was invited via email and was somehow convinced that it was a good way of keeping track of people. But I completely forgot about it the very next day. The only thing that kept reminding me that I had a twitter account was the countless emails I got almost every week saying that I have a random person following me. You can't even post pictures much less have people comment on them like you can in facebook. I can't think of any other negative factors on Twitter as I can't think of any features..since it doesn't even have any! Facebook does have its downfalls but it should definitely knock Twitter out of the program! I have no idea why it hasn't already..