Difference Wait Time

Wait Time is the cumulative wait time for the time period (in your case 4AM to 5AM) for the SQL hash

Total wait time is the cumulative wait time for the same time period for all the SQL queries

% of Total Wait Time is the percent of these two numbers, i.e., how big of an offender is the SQL query you are looking at.

Another Questions I have.

1) Everyday between 4 to 5 am for the SQL Hash is the cumulative ? then its suppose to different value in next hours and it should not cumulative of the previous hour. But in reality, the total wait time is difference.

The total wait time represents the aggregate wait time of the SQL displayed (by default the top 15 statements).

When you hover over a specific SQL hash, the wait time represents the waits just for that statement.

Both of those numbers are specific to that time period, so 1 hour. These are not cumulative across hours (they are specific for the timeframe stated).

To get waits for other time ranges, you can change the interval for the current trend graph or you can even define a custom time interval.

HTH.