Furthermore and Moreover > interchangeable There are close synonoyns >meaning " in addition " They can be used to link 2 sentences as a transitional adverbs , not conjunction ,such as "and " and but" . So, since there are not conjunctions you have to put a semi-colon before and a comma after these 2 words when you join them (not a comma) , or you can break them into 2 sentence . It is not too show "similarities" but to "add" to what you said earlier with something that is of interest or worthy of mention ( in your opinion) I love this job because it pays well , moreover, it's very near to my house X I love this job because it pays well ; moreover, it's very near to my house I love this job because it pays well . Moreover, it's very near to my house I love this job because it pays well ,and it's very near to my house ( using conjunction "and")

They are interchangeable. You use them in the context of creating more evidence for your point. "Smoking is bad. It seems to me that inhaling smoke cannot be good for you. Furthermore, scientific studies show that...."