Summarize or Summarize Column not results same Data comparing to default aggregation on that column

 Hi Community Legends,

I've just start learning DAX and tried Summarize on Page4

but not getting same result if try to use default sum aggreagte on that column.

So used below query to create new table , but if choose Name and Unit Cost in a Visualization Type Table results are not same.

SUMMARIZECOLUMNS (
Customer[Name],
"SumOfSales", SUM ( Sales[Unit Cost] )
)