http://www.espn.com/nhl/story/_/id/...-replica-jerseys-stanley-cup-champion-apparel
There are no direct comparison pictures yet but its not too different from when Reebok did both.
There are three tiers of jersey
Replica - Cheapest jersey, what you most often see in retail stores. Lighter and thinner material. Heat pressed logos and lettering. For Reebok the shoulder patches were a single layer plastic patch and the crest was fabric. The new fanatics replicas will use the plastic material for both shoulders, crest, and lettering. Its crap.
Retail Authentics - Made by Adidas in Indonesia, closely replicates the on-ice style of jersey. Last time around the main difference was that the fight strap was not double reinforced, and the neck tag. They used to go for about 300USD, the Adidas version of these are going for 220USD-260USD per team retailers, which is nice.
On-Ice Authentics - Made by Adidas in Canada, exact on ice version of the jerseys. These can only be ordered by Teams directly and not third party suppliers. Many teams will likely sell surplus through their team store(Canucks were doing this up until last season iirc), or they end up with third party resellers.