D10 gives you the chance of simple percentage based rolls so you can factor in more things (range, terrain/cover, aiming etc).
D6 is more complex for factoring in the difficult stuff, and the only easy way to factor in is to use 2 rolls, a shooting roll (modified by aiming, possibly range) and a save roll (modified by cover and possibly range if it wasn't in the other modifier).
But 2D6 don't convert so easily to percentages so you'd need to google the percentages (unless you're good at maths analysis).