Acquired a set of steel wheels for the wife's 08 Sport. Came with a set of steel wheel lock nuts - what would be the difference between these and the alloy wheels lock nuts?

I also got the steel lug nuts along with the wheels but why couldn't the steel wheels be attached to the hubs with the alloy wheel lug nuts - thinking about salt residue getting into the end of the open steel lugs...

 

are they both round where it contacts the lug bores?

generally speaking there are 3 different types of lug contact
areas. tapered, round, flat.

 

They are both ball contact - so I wonder why Honda makes different lock nuts for wheels for the same vehicle - does it have anything to do with length?

 

yah, possibly. the smaller ones might not be deep enough when you run the steelies.