Yes, they're just different styles of hand-writing those letters. Usually they're more calligraphic-y, but for example I've always wrote \vartheta instead of \theta and my dad always writes \varpi instead of \pi. And while I just have awful, sloppy handwriting and I find \vartheta easier to write (easier to not try and hit the other end of the circle) my dad is just being posh :)

With the exception of the ς which is as you say, the form used at the end of words (I don't know why- probably something to do with ancient writing styles).