Actually, some consider the SFOD-D to be even more capable than the Navy SEALs. While the SEALs main function is to be a highly specialised, quick reactive and proactive force, SFOD-D operators are trained to be blend into a hostile environment. The hierachy within a Delta unit is very blurred, because operators refer to higher ranking members by names. This lack of formality is meant to allow operators to appear to be friends, tourists, adventurers even, within a hostile environment. The scene in the film Black Hawk Down where a Delta operator (Banna) is shown to be working alone and unarmed with the people who live in Mogadishu is a very accurate illustration of what Delta operators do in real life. They work within the local population to collect information on targets and subjects of interest. Delta operators have huge allowances compared to the rest of the regular armed forces. They grow beards, wear uniforms that really don't resemble anything like regularly US military garb (assuming they aren't simply fighting in civilian or local clothes) and use unconventinal weapons (Delta actually allows it's operators to select any gun they like from anywhere in the world to be kept in the base armoury as their primary weapons, as long as they aren't hard to acquire. want a Russian pistol? Not a problem, just fill in the request form).
Easier to blend in with a bunch of commies using a russian weapon than a Nato one definitely. Also sometimes, it's the ease of getting your rounds after you expended some...