A sonnet needs more than 14 lines ...

[kickassangel]

To make it a sonnet.

I have recently come across various 'sonnets' which are 14 line poems, with a rhyming scheme (usually ABABCDCD) and a very rough number of syllables per line. Anywhere from 6 to 13.

Those aren't really sonnets are they? They are poems that are 14 lines long.

There is a difference.