What is the difference between CCA, CA, MCA and HCA?

They are all measuring the cranking amperes of the battery but at different temperatures. A lead-acid battery will perform better at room temperature than in freezing temperatures.
Cold cranking amperes (CCA) is measured at -18C (0F).
Cranking amperes (CA) is the same as Marine cranking amperes (MCA) is measured at 0C (31F).
Hot cranking amperes (HCA) is measured at 26.7C (80F).
For example a battery rating 600CCA would be roughly 750CA (MCA) and 900HCA.
CCA is predominantly used in Australia to compare batteries. The only real problem is when consumers are comparing CCA rating between batteries some manufacturers are more conservative in their ratings.