Basic Difference between Last Time Period and Previous Time Period

 
What is difference between last time period and previous time period? For comparison, if i put the query for show data from last 7 days to previous 7 days.... either both are same or different? 
 
no one is there who can help me to understand what is basic different between Last and Previous time period?
 

It depends on your comprehension

Last 7 days is the last 7 days

Previous 7 days is the 7 days previous to the last 7 days

When you use the word previous, there must be something for it to be previous to.

So instead of saying the last 7 days, you may so the 7 days previous to today.

Others may see it differently.

Why is it important?

 
Keith Watford:

It depends on your comprehension

Last 7 days is the last 7 days

Previous 7 days is the 7 days previous to the last 7 days

When you use the word previous, there must be something for it to be previous to.

So instead of saying the last 7 days, you may so the 7 days previous to today.

Others may see it differently.

Why is it important?

thanks for your response! 

its really important for me to check out my trading history. To analyse what was reasons for my lose in last 7 days or 7 previous days.