1. Overall
The provision on terms and definitions is included in Chapter 1 “General Provisions” and this chapter consists of four main provisions.

There are only a few terms that are defined, and the definitions do not really say much more than what is implied by common parlance. We have chosen to treat the subject in the same way as the others.
2. Rule mirror

3. Briefly about the concepts
The seller is the one who has undertaken to either deliver the construction product or the product. Who the seller himself gets his deliveries from, in this regard is not important. Nor whether the seller has to hire assistance in order to produce the product the parties have agreed. By contrast, the scope of the seller's duties in a contract based on NS 8412 will normally be far more extensive than in a purchase covered by NS 8412. The seller is the buyer's contractual counterpart, and vice versa.
Buyer is the one who will receive the construction product or product delivered. In both cases, it is the buyer who must define what is to be delivered by the seller, but the scope of buyer's definition will be different between the two forms of purchase. We do not think it is unnatural to say that it takes more effort from the buyer to define what is desired when one has a relationship covered by NS 8412 compared to NS 8411.
NS 8411 paragraph 2.3 defines “construction goods” that the seller is to deliver to the buyer, while NS 8412 paragraph 2.3 defines “product” that the seller is to manufacture and, if necessary, assemble for the buyer. This may not say much, since there can be a lot of differences. It may be that you get a more comprehensive understanding when you also read the article on clause 1.2 of the contracts “Intended Area of Use”, that can be read here.
In addition, it may be appropriate to problematize another side by the term “Products” which is not stated in point 2.3, but in point 1.2 It states that NS 8412 is intended to be used on all products “including installations and facilities”.
A product manufactured by the seller appears — at least to us — as something limited and concrete. In short, an object that is first delivered to a construction site, which corresponds to the buyer's specifications and which — after delivery at the construction site — is incorporated in a specified manner into a building or plant. Either by the buyer himself or others the buyer has engaged, or by that “the product” assembled by the seller upon further agreement. An installation, on the other hand, appears as something larger and more complex than a “product”. As we think about this term, an “installation” could consist of several products assembled in a certain way, but we find it a bit strenuous to envision multiple installations put together into one “product”.
We raise this issue because it follows from point 1.2 that sometimes it may be more natural to use one of the standards of contract law such as NS 8407 rather than NS 8412.
If the seller is to deliver a ventilation unit according to a detailed description from the buyer and where this is mainly produced at the seller's premises, the unit will presumably be a product and the agreement is based on NS 8412.
In another delivery, the situation may be that the seller will deliver an installation consisting of an aggregate with ducts, dampers and all that belongs to a working ventilation system, or a ventilation installation. In such a case, a number of products will have to be assembled on site and the job will be far more complex and laborious - while the work takes place outside the seller's own place of business. In that case, it would be natural to characterize this as an enterprise governed, for example, by NS 8407, and not an acquisition regulated by NS 8412. Then it is no longer a purchase, but an enterprise. We are then not talking about a product or an installation, but about a contract work. However, the decisive factor here is not the concept of “installation”, but how much of the work is actually carried out at the place of delivery (construction or construction site).
Finally, we have the term “fitting” which in NS 8412 paragraph 2.5 is defined as “all work (...) necessary for the product to be built in”.
The assembly work shall be done at the installation site which is, as a prerequisite, on a construction or construction site and in accordance with the agreement of the parties.
If we refer only to the use of concepts, it appears that “mount” to be less time and labor intensive than an enterprise. At the same time, NS 8412 contains rules on preparation for, and execution of, takeover business. It is only after the completion of such a takeover transaction that the buyer is delivered the product when assembly is included as part of the agreement. As part of the takeover, testing and regulation shall be carried out where relevant, in which case test documentation shall be sent to the buyer at the latest together with a notice of takeover business, etc. Consequently, it must be stated that NS 8412 contains provisions which are very recognisable from the standards of contract law. We will therefore assume that NS 8412 is expected to be able to be used on relatively large and complex procurements.