Thanks ladies! I have been using plates, cups, lids etc to round things off but thought these two rulers might add something different to the process. Couldn't see for myself how the radius' were different....duh. Thank you Macybaby. So the round up tool has the 4 and 5" radius and the corner cutter has smaller radi. These may well fall into the " I think I might like them, but don't really NEED them category.
Will just leave them in my Amazon shopping cart until the urge passes.....lol or I find a need for a specific radius on something.