xlsnams <- grep("XLS\\.", names(DB.SpotifyMeta), value=TRUE, ignore.case=TRUE)

nams <- gsub("XLS\\.", "", xlsnams, ignore.case=TRUE)

stopifnot(all(nams %in% names(DB.SpotifyMeta)))

DB.SpotifyMeta.cols <- c("upc", as.vector(sapply(sort(nams), function(x) paste0(c("XLS.", ""), x))))

write.csv(
DB.SpotifyMeta[Reduce("|", mapply(function(a, b) tolower(get(a)) != tolower(get(b)), xlsnams, nams, SIMPLIFY=FALSE)), .SD, .SDcols=DB.SpotifyMeta.cols]
, file=as.path(outDir, "Discrepencies.csv"))