It's an adjectival clause meaning that it tells you exactly which "kinds of behavior" are being talked about. Removing it would mean that the listener didn't know which "kinds of behavior" were meant. The sentence is not about all "kinds of behavior" and it's not about any old "kind of behavior". It's about "the kinds of behavior referred to by the term." As long as the term, and the kinds of behavior it refers to, have been firmly established prior to the sentence you quote, and the reader can be relied upon to still have them in mind and no others, then you could say "There is more agreement on those kinds of behavior than there is on how to interpret or classify them." "Those" is the key word there, because from that single word the reader must be able to reconstruct the concept of exactly *which* kinds in order for the sentence to be understood.

I think the sentence just means: "There is debate about whether these behaviours should be classified under this single term." The sentence appears to have two parts. 1) The term is widely used as a general description for a specific group of behaviours. 2) However, there is a sense that some behaviours could be described better using other terms.

Quite the contrary - if you removed the words "referred to by the term," the sentence would cease to make sense at all. Just reading it alone, I can tell that this sentence is from the middle of a paragraph (again, otherwise it wouldn't make sense). The preceding sentence introduced a word or a phrase. This sentence expands on the idea previously introduced and is saying something additional about the word or phrase (basically that it's easy to pick out examples of that word or phrase, but it is hard to create a classification system for them) Unfortunately, I can't find the original context for this sentence. All I can find is what seems to be some translation exercise, all of which have various levels of context (and because of that, the sentence stops being sensical.)

Original quote (which actually makes sense): "There is more agreement on the kinds of behavior referred to by the term 'intelligence' than there is how to interpret or classify them." So, perhaps your quote, in full, should be "Intelligence. There is more agreement on the kinds of behavior referred to by the term than there is how to interpret or classify them." A simpler or shorter way of saying "referred to by the term" is "meant by the term".