table difference Totals vs Line Item

Dear SDN,

As do not have access to BW / R/3, I would like your help to know what is the difference between total level record vs a line item level record for FI-SL.

I would think most of the characteristics and keyfigures are the same for totals and line items table. But what is the difference then? I know line item has more details and totals should be somehow aggregated data. but what is the aggregation factor or field? How is aggregation realised?

Thanks

Adette