You are spreading some misinformation with a lot of conjecture. They are manufacture by the same plant but they have two different SOC designs. Samsung didn't design anything in-house.
They hired SOC designers to give them the blue-print, namely Intrinsity. They give this blueprint to a fab plant. That fab plant happens to mfg the same SOC for another company.
All ARM architectures share certain traits. They all license the core from ARM. Then they build around it. It depends on the mfg to tailor make them for their needs; changing the I/O, changing the memory controllers, gfx sub-system, etc..
It is the same when you buy a motherboard. Asus, Acer, whoever put in their PCI bus, memory controllers, etc. You have mini-pci, ITX, different classes of motherboards.
Saying which one is better is a bit intellectually naive without merit. One processor was designed for optimal battery life and one was designed with a higher 3d gpu core.
Then you have the different OS optimization. It is like saying a Mazda R8 is better than a iron block corvette because it revs its engine at 9,000 rpms vs 3,000 rpms. Two different designs.
If you look at the x-ray scans of the a4 vs something like the snapdragon, they took out a lot of un-necessary stuff they didn't need and shrank the die core. Hence, they were able to add a significanty larger battery within the same foot-print.
If they weren't serious, I don't think they would have spent $121 million on buying out Intrinsity.
This is the best article on the subject and the source infor of the 1st quote.This is the article where everyone gets their source without crediting it.
Apple's A4 dissected, discussed...and tantalizing
Again, the EETimes provide fodder for arstechnic. They summarize the EETime research in layman, common-folk terms for you to understand.
A closer look shows Apple's A4 is "tailored," not "bespoke"
If you take anything from the original article, this quote is the most relevant.
Bottom line. Both Samsung Hummingbird and A4 are unique SOC designs exclusive to the two manufactures whereas the Snapdragon is sold to anyone who wants to buy it. A Snapdragon system may have a lot of un-necessary bulk and overhead versus a bespoke SOC system.