SUM and ACCUMULATE?

%_sum_value = SUM(table[value])

%_accumulate_value = 
CALCULATE(
	SUM('table'[value]),
	FILTER(
        ALL(table),
        table[date_time] <= MAX(table[date_time])
	)
)

The main difference between %_sum_value and %_accumulate_value is that the former calculates the sum of the value column in the table table, while the latter calculates the accumulated total of the value column up to the maximum date in the date_time column of the table table.

Specifically:

%_sum_value uses the SUM function to calculate the sum of the value column in the table table. This formula does not apply any filters or conditions to the data and simply returns the total sum of all values in the column.

%_accumulate_value uses the CALCULATE function to apply a filter to the value column in the table table based on the maximum date in the date_time column. The FILTER function is used to remove any filters on the table table, and then apply a filter to select only the rows where the date_time column is less than or equal to the maximum value in the column. This filtered subset of rows is then passed to SUM, which calculates the accumulated total of the value column up to the maximum date in the date_time column.

In summary, %_sum_value calculates the total sum of the value column, while %_accumulate_value calculates the accumulated total of the value column up to a specific date. The latter formula applies a filter to the data based on the maximum date in the date_time column before calculating the accumulated total.