What is the difference between inboard and outboard engines on a Russian IL-18 turboprop? I was looking at this picture of an Ilyushin IL-18 turboprop aircraft
Image hosted at https://i2.cdn.turner.com/cnnnext/dam/assets/160630220221-north-korea-air-koryo-il-18-nose-super-169.jpg
 and noticed that the outboard engines look significantly smaller than the inboard engines. Wikipedia lists specifications for four identical engines but the outboard cowlings don't seem to have air intakes. 

Can anyone explain why?
The inboard cowlings seem to follow a different design structure in order to make room for the landing gear compartment. The air intakes are moved aft on the outboard cowlings.