Which should be used: aoColumns or columns?

I wanted to have a custom sort function for a column in my table. I could find an example, which used aoColumns option, and my goal of custom sorting is achieved as well. However, is aoColumns a legacy option? Should I be using columns option?

This is how my datatable initialization looks:

myTab.DataTable({
aoColumns: [
{"sWidth":"40%", "bSortable":true},
{"sWidth":"60%", "bSortable":true, "sType":"customDate"}
]
});

Thanks.