How do i differentiate between syphillis chancre and chancroid?

Many differences: The syphilitic ulcer has a hard base which is non-tender, has a well-defined edge and will, with time, disappear on its own. The chancroid ulcer has a soft base, is quite tender and may look inflamed, and has ragged shaggy edges. You should not try to make this diagnosis yourself, but see a doctor, because if you have one std the odds are good that you have more than one. Get tested.