I'll be the first to admit I have no clue how to use 礼节， but I can tell you this.
品茶是一种礼节. and not 一种礼貌。
How I understand it, 礼貌 is a collective noun essentially meaning 'manners'。
礼节's uses are a bit more complicated. How I see it, it means a few related, but rarely used concepts in english: "ceremony", "protocol/custom", and "etiquette."
Understanding it as etiquette is not particularly useful as like 'manners' it is a collective noun with little real difference in use/meaning. Understanding it as a 'custom/protocol' or a 'ceremony' that is relating to etiquette/manners is the only way to make it's use understandable in English. Just remember that these 'protocols' and 'customs' are different, at least slightly different from customs (风俗） which I am hoping you already have a good grasp on because I don't feel the need to explain something like that because to an english speaker, those customs should be more understandable.