Difference from previous period (in YYYYMM format)

chandakaushik , better is that you create a date , as suggested by lbendlin, and use a date calendar.

And create measures like this

MTD Sales = CALCULATE(SUM(Sales[Sales Amount]),DATESMTD('Date'[Date]))
last MTD Sales = CALCULATE(SUM(Sales[Sales Amount]),DATESMTD(dateadd('Date'[Date],-1,MONTH)))
last month Sales = CALCULATE(SUM(Sales[Sales Amount]),previousmonth('Date'[Date]))
last MTD (complete) Sales =  CALCULATE(SUM(Sales[Sales Amount]),DATESMTD(ENDOFMONTH(dateadd('Date'[Date],-1,MONTH))))
previous month value =  CALCULATE(sum(''Table''[total hours value]),previousmonth('Date'[Date]))

diff = [MTD Sales]-[last MTD Sales]
diff % = divide([MTD Sales]-[last MTD Sales],[last MTD Sales])

The second way is to have month year table (Your month are sortable) and create a rank. You need to have a separate table.

Month Rank = RANKX(all('Date'),'Date'[Month],,ASC,Dense)
This Month = CALCULATE(sum('order'[Qty]), FILTER(ALL('Date'),'Date'[Month Rank]=max('Date'[Month Rank])))
Last Month = CALCULATE(sum('order'[Qty]), FILTER(ALL('Date'),'Date'[Month Rank]=max('Date'[Month Rank])-1))

To get the best of the time intelligence function. Make sure you have a date calendar and it has been marked as the date in model view. Also, join it with the date column of your fact/s. Refer :
https://radacad.com/creating-calendar-table-in-power-bi-using-dax-functions

Appreciate your Kudos.