A lot of the information in that post is inaccurate or inconsistent.

For example, the only Classic series 737 that can be retrofitted with winglets is the 733; the 735 pictured in that article is a 73W.

The author focused too much on information that wouldn't matter to a planespotter (this article was supposed to be a planespotting tutorial.) For example, there is no way to discern, by looking at a plane, whether or not it has fly-by-wire technology.

Furthermore, the "fly by wire" the author refers to is Airbus' flight management computer doing most of the flying, as opposed to direct controls in a Boeing airplane. All NG 737s, for example, have fly-by-wire technology.