Steady on now. I'd say that both OCD and depression are on a spectrum. There's no switch that suddenly flips you from 'low mood' into 'clinical depression', and indeed different doctors might diagnose people with the same symptoms enitrely differently. And there are plenty of people with aspects of OCD that lead perfectly normal lives.
OCD is most definitely not having a voice in your head that's telling you to kill people - that would most likely be some kind of untreated and very severe schizophrenia.
Absolutely, definitely, and completely having to line all of your pens up before leaving the house, despite knowing that it makes no sense, and will make you late for work etc., is more like OCD... imho. Just liking things properly in order is the sign of a tidy mind. Which is why I won't eat my alphabetti until it looks like this...