What Makes a Drop tower scarier than a rollercoaster?

I went to six flags the other week and i love rides!! dont get me wrong! but there was a rollercoaster that was a tinch higher than the drop tower there. Like a tinch. at the top of the rollercoaster as it went over the crest it was scary and fun. But how can you be pretty much the same height on the drop tower and it feels a little more uncomfortable?? you know. i was on one that leaned the freakin seats forward and it dropped! lol. What makes it more weirder feeling than a rollercoaster. Your opinion!