What does it mean to be "89% close to" Agave when it comes to DNA? Are we talking genetic similarity, or estimated likelihood of a match? Considering that a hu

What does it mean to be "89% close to" Agave when it comes to DNA? Are we talking genetic similarity, or estimated likelihood of a match? Considering that a human's genetic similarity to a cat is 90% and even to a banana is about 60%, 89% doesn't sound like all that much.