What is different between low and high cation exchange?

http://www.spectrumanalytic.com/support/library/ff/CEC_BpH_and_percent_sat.htm

Low cation exchange		High cation exchange
Soil with a low CEC value is a good indication that a soil is sandy with little or no organic matter that cannot hold many cations. Sandy soil		A high CEC value is a good indicator that a soil has a high clay and/organic matter content and can hold a lot of cations. Clay soil
˂5	CEC value	˃25
Lower	Present of clay and organic matter	Higher
Lower	Water holding capacity	Greater
Potassium and magnesium  (and other cation) deficiencies. A large one-time addition of cations (e.g. potassium) can lead to large leaching losses as it is soil unable to hold on to the excess K.	Deficiencies of cations	Less susceptible to leaching losses of these cations
the faster the soil pH will decrease with time.	pH vs time	the slower the soil pH will decrease with time.

References:

1-      http://nmsp.cals.cornell.edu/publications/factsheets/factsheet22.pdf

2-      http://www.spectrumanalytic.com/support/library/ff/CEC_BpH_and_percent_sat.htm