This is an injection-plastic aircraft model kit.
With both major aircraft model firms releasing a 1/72 Mosquito within months of each other, one is certainly tempted to compare, and compare we have. The results: Tamiya has a better kit, but only by a tiny margin.
The major differences are in the finer details. Something about the access panel covers on the wings and fuselage of the Tamiya version just look a bit better, but in this scale, and when painted, it's questionable if one could tell them apart. One major difference is the canopy. Hasegawa's is two-piece, split down the middle on the center railing. Tamiya is a one-piece affair. Some of the other little points are a bit better in the Tamiya kit as well, and since it's 500 yen cheaper...
Hasegawa owners have no need to fret. They own a superb kit, too. And Hasegawa is more likely to produce a number of more minor variations than what we can expect to see from Tamiya.
This kit is a 100% all-new Tamiya tooling, not an Italeri import reboxed for Japan.