The documentation says
Enumeration to specify whether the Data Dictionary contains equal features
Could someone give more details? What confuses me is that how HomogenNumericTable can have unequal features.
Also, when Matrix should be preferred over HomogenNumericTable?
HomogenNumericTable assumes the same data type for each value, but per-feature attributes may be different. For example, you may have 2 features, both are integers, but first one is continuous feature and second one is ordinal feature. In this case, you must specify that features are not equal.
Regarding to Matrix class, it depends on language you use. For instance, in Java API of DAAL, Matrix supports additional setters and getters relative to HomogenNumericTable.