Primarily, "Ira" is an emotion whereas "furor" is a behaviour. However, figuratively, you can, by metonymy, speak of a "furor" raging in your heart, or describe a storm as "ira Deorum", or whatever.
What does Ira Furor Brevis est mean?
: anger is a brief madness.
What is Furor Brevis legal?
Ira furor brevis est is a legal maxim in Latin. This maxim states that anger is short insanity. The following is an example of a case law referring to the maxim: The benignity of our laws respect, to a certain extent, the frailty of our nature.