You don't say what "gun" you want to use them in. Others have assumed you are talking about C&B revolvers.
If using soft lead either will be just fine as long as you get a little shaving of lead on seating into the chamber.
Using a .451 ball in a ROA might "work" but it is not the best choice. Regardless of wads, etc. you can still get gas blow by in the cylinder and lower velocity. It also might not swage properly in the forcing cone and degreade accuracy. It 'might' be OK and might "work" but always best to with proven methods.