I don't think we can argue which were the "better sailor" as both had sailing techniques which were developped in response to different problems.

So to answer your question; yes. The basic rules of wind based navigations are pretty universal, having sailed a bit myself as a sport when I was younger you are taught using small one or two men crewed boats and slowly go onto bigger ones like a catamaran. Although they are very different beasts what you learn on a small one applies well to bigger ones aswell. Obviously complexity grows as you go up in ship size, it's harder to move the sail of a caravelle than off a catamaran but the reasons why you should move it and following what rules stay the same.

Now we are talking about two completly different types of ships, not just ones that differs in size so that adaptation time would be longer but I believe both would absolutly be able to figure out how to operate the other's ship, longboat or vaka purua. However they would quickly realise that those ships are completly useless as they weren't designed for their needs. A longboat is a low hauled ship, lightweight and with a single quadrilateral sail. A vaka purua has two hulls linked by a central plateform and usually two triangular sails, although Polynesian canoes varied in size some were very large and able to contain potted plants and even animals carried over onto islands to colonize. They were up to 25 meters long and could embark up to 50 people.

The first big difference is the sail's size and shape, the bigger longboat sail and it's shape gave it better speed than their Polynesian counterpart, however this type of sails is very bad when trying to navigate against the wind, which wasn't as much of an issue in the seas were the Norse navigated as it was in the Pacific. Quadrilateral sails are also more resilient which is useful in the generally harsher conditions of the north sea and explains why triangular sails in Europe were first adopted in the warmer south, in Italy and Portugal for example.

The other difference is the hull, the longboat as a single haul whereas the vaka purua uses two. Now it's not as much of a difference as the sail, polynesians also used single hulled ships called vaka kumete, but the dobble-hulled variant was the most popular because it made "tacking", a technique used when navigating against the wind, easier and safier, something that wasn't a concern for the norse.

To conclude given enough time both group would absolutely be able to use the other's ship, however they would be off little use as both designed their preferred vessels in accordance to the needs of navigating on their seas, making comparing them and saying which is best a pointless exercice. Want to navigate in the north sea ? A longboat is your best option, but in the pacific the vaka is king.

There's no real reason why one or the other could not -- I've sailed a few vessels from fore-and-aft Bermuda rigs down to an itty bitty Sunfish and the principle is the same. A Polynesian ship is more equipped to sail against the wind in the sense that most of them have what are described as Oceanic lateen, or sometimes crab-claw, sails, while the traditional "Viking" ship (which we only have a few examples of) generally had a square sail, but could use oars when traveling into the wind. The major difference between Polynesian navigators and Viking navigators is that he former explored a massively larger portion of the earth's surface, being that the Pacific is larger than all of the Earth's land area combined, and that Polynesians settled land ranging from New Zealand to Easter Island and Hawaii, and likely made contact with the Americas in the late 14th century.

Is there something specific you'd like to know about the differences in their sailing style?