So, for us non-Russophones, which book is potentially more useful to the illiterate modeler? More photos, more useful photos & illustrations etc.?
Both books are written by historians for those interested in history,
not for modellers... If you are looking for "walk-around" photos, you will not find them.
Ivanov's book is thicker (220+ pages),
more photos (but smaller!), more colour profiles, more line drawings. There are even few pages with colour photos of planes preserved in museums (again small and not very useful for modelers).
Maslov's book is thinner (120 pages),
less photos (larger and better reproduced). Few pages are dedicated to M-11 engine, there are more photos of details in Maslov's book.
If you don't care about the text, Maslov's book is probably a better choice. The best choice is to buy both books - they are not expensive...