A large number of pre-finished and engineered hardwood flooring manufacturers re-tool quite often making it difficult to get a matching product after a few years, both in color and/or material description. ie: thickness of the wear layer, thickness and width of product, compatibility of the tong and grove, discontinuation of stain colors, etc. Also the majority of pre-finished manufactures make their products with micro-bevels and restrict product length to less then 3-1/2 feet.
There are exemptions to the norm, and if an engineered floor is needed I recommend Owens Flooring by ColonialCraft with a wear layer of 3/16", widths of 2-1/4" to 6", standard lengths of 1' to 8', and custom length up to 12'.
The manufacturing of solid unfinished hardwood flooring has long been standardized here in the U.S. Solid 3/4" flooring has a "wear layer" of 5/16" and random lengths from 1' to 7' feet, with an average of 3-1/2 feet, and custom lengths of 8' to 12' feet. Unfinished flooring comes with or with-out bevels. Solid hardwood flooring is what all engineered and pre-finished flooring is trying to emulate.
Both types of flooring can be installed by ether nailing to a wood sub-floor, or gluing to a concrete substrate, or floating. Floating floors will tend to sound hollow and move up & down as you walk over them.
With engineered flooring one of the most important things to consider is the thickness of the wear layer or actual hardwood. The thicker the wear layer the more times the floor can be re-sanded. Solid wood flooring with a 5/16" wear layer can be re-sanded 10 to 12 times, while a engineered floor with a 3mm wear layer can only be re-sanded twice. Other considerations include: future availability of product and product color, and the length of the individual hardwood strips or planks.