Difference between Constant mode and Exact mode

Today I saw how my machine was not doing round circles at all, and found this is a problem with the Constant Velocity Mode (and its parameters). I expected Constant mode to be a problem with lots of small straight lines, but not with circles. I was wrong.

Changing it to Exact Mode in the configuration tab of UCCNC, I achieved perfect circles at the expense of more machine time.

Take this into account for any project where you need precission.

Sorry for the bad quality.