Recently I had bit titan migration and the Sharepoint Document Library size of the Source Tenant was 2TB and the destination was only 200GB , quite a bit different , however Bit Titan said everything had copied ok, but I wanted to make sure all the files were there

You can show Storage Metrics for a nice overview

There are a few reasons why the sizes might not be like for like 

1. Bit Titan only copies the last 3 versions
2. Recycle bin isn’t copied

How do you compare Source to Destination to make sure everything had copied ok?

1. Export both Document Libraries to Excel 
   

   

2. Check Column A the Name Column , this is populated with Folders and File names , halfway down my both lists I was getting actual full file paths from some of the files  
   
   

   https://xxxxxxx.sharepoint.com/sites/Data/Shared%20Documents/xxxxxx/xxxxx/xxxxx/xxxxxx.pdf

   
   This won’t work as the file paths will be different , so I used Excel to give me the file name only 
   
   =RIGHT(A77318,LEN(A77318)-SEARCH(“#”,SUBSTITUTE(A77318,”/”,”#”,LEN(A77318)-LEN(SUBSTITUTE(A77318,”/”,””)))))
   
   
3.  I then copied both columns into a new excel document , selected all and ran a unique compare
   
   

   
   
   

   

4. Anything marked as red are the missing files!