Are these the same film stock?

I shoot Fuji's disposables a lot and really like the colors.
In Japan they are called "Simple Ace" (シンプルエース), I think it's the same as "Quick Snap" in the U.S.

The disposable film really works on overcast as well as sunny days.
I would assume that it's Fuji's cheapest 400 speed film, but the cheapest 400 film here in Japan is Superia X-Tra 400 and that seems a little cooler in color than the disposable.

The edge markings look very similar but I am not sure if they are in fact the same film.

My guess is that they are different. But that is just a guess. It is hard to compare the negatives, but they have a different "look" to me. The edge markings at the bottom are similar, but they are not the same. At the top, one film has machine readable markings and the other doesn't. That may or may not be significant. Also on the top, one is marked "H-74" and "PF-34" while the other is marked "CH25". There are quite a few differences, but it still could be very different batches of the same film; still, my vote goes for different.

I have looked at your very good and clear photo of the two negatives. From what I can see I would suggest that the top one is an own brand Fuji 400. The H74 is a production code and a quick qoogle showed that this number is for Agfaphoto Vista 400, which is made by Fuji.

The bottom negative has the markings of Fuji Superia Xtra 400 (CH code).

As far as I know most Fuji made own brand films are one generation emulsion behind current Fuji brand. Think of Fuji Superia 200 and Fuji C200.

Since Superia had the forth layer and the C200 doesn't, then I suggest they are different films made by Fuji

the top one with the H-74 PF-34 markings is film from Fuji's disposables here in Japan. The other one is normal Superia X-tra 400. So the disposables do have different film.