Real difference is between IPCC 4.x and 5.x. Difference between 4.x version is different CCM supported.
4.0(x) is for CCM 4.1 and 4.2 (winOS - windows 2000), ipcc 4.1(x) is for ccm 4.3 (winOS - windows 2003), ipcc 4.5(x) is for ccm 5.x and 6.x (winOS - linux).
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regards,
PK