basic doubt about ITAB

Dear All,

techinicallly is there any difference between.

data : it_mara type standard table of mara.

t_mara type mara occurs 0.

Which is better way to define. I know both are internal tables without header.

onemore thing, header that it is obsolete to use "occurs 0", is this right.

Please let me know.

Regards

madhu