drosophila reference genome - flybase >6 - explanation of files

Question

[cpak1981]

I'm looking to download the latest D. melanogaster reference genome. In the link, I see, dmel-all-chromosome-r6.18.fasta.gz, which is what I think I want. But I also see dmel-all-aligned-r6.18.fasta.gz and I have no idea what is represents and how it differs from the first file. Any explanation or link to an explanation would be very much appreciated!

[mufernando]

did you figure this out? if you did, please explain it to me!