well, lets compare both to compounding once a year for n years.
Once a year
final/original = 1.06^n
Four times a year
6/4 = 1.5% per quarter
final/original = 1.015^4n
Continuously
final/original = e^.06 n
Well, lets see how four times a year compares to once a year
compare 1 = 1.015^4n / 1.06^n
ln compare 1 = 4 n ln 1.015 - n ln 1.06
= n(.05955445-.0582689) = .0012855419 n
so
compare 1 = e^.0012855419 n
or .12855 % better than once a year
Now do the same for continuous
compare 2 = e^06 n / 1.06^n
ln compare 2 = .06 n - n ln 1.06
= .001731 n
compare 2 = e^.001731 n
or .1731 % better than once a year