Fuzzy Logic is all about degree of truth what is the Probability theory about the chances of occurrence (or non occurrence) of an event (its chances not truth).

Lets see an example to find out the difference -

Suppose that I'm standing in your office doorway with one foot in your office and one foot in the hallway. It's reasonable to say that I'm half in your office (as in fuzzy logic), but it's not reasonable to say that there's a 50% chance that I'm in your office (as in probability).