Every scouting body? Every scouting body were scouting two different drafts how could they rank one or the other above each other?
That's what "relative to their peers" means. Filatov was considered a better prospect relative to the kids in 2008 than Nylander was compared to kids this year. Assuming you consider 2008 at least as strong a draft as this year (many people would IMO) it holds that Filatov was ranked above Nylander.
Though I wouldn't be so put off by the Filatov comparison really. He busted not for lack of talent - he was sublimely talented - but for lack of heart and desire to succeed in North America (IIRC). Nylander is by no means destined to end up like Filatov though it is a fair cautionary tale for anyone who feels Nylander is too talented to bust as _no one_ is too talented to bust.