What is the difference between data tables & layout tables defining role [closed]

In Accessibility What is the different between Data Tables & Layout Tables.

any important to use role="presentation" in tag.

for example

<table role="presentation>
   <table role="presentation"></table>
</table>

or

<table>
  <table role="presentation"></table>
  <table role="presentation"></table>
  <table role="presentation"></table>
</table>