Differentiating the choices
How can I differentiate a smooth+cigar shaped from disk+edge on+no bulge?
Welcome to Galaxy Zoo, beng5113!
In a word, with great difficulty! 😮
A rule-of-thumb I use for 'edge-on' is 'does it have pointy ends?' (if so, it's an edge-on). If the galaxy is big enough - takes up enough pixels - you can sometimes distinguish 'smooth+cigar shaped' from 'disk+edge on+no bulge' by how sharp the nucleus appears ... 'smooth+cigar shaped' will have a smooth gradient with no sharp breaks, but 'disk+edge on+no bulge' will have just such a break. Also, highly inclined disks - not quite edge-on, so they look cigar shaped - may have structure, a hint of an arm or a bar perhaps, or a ring or lens. None of this helps much if the galaxy is small, of course. 😦
Ultimately, however, it's your choice, call it as you see it (there is no "right" answer).
Happy hunting! 😃