Time Machine/Time Capsule: What is the difference between "Waiting for index to be ready (100)" and "Waiting for index to be ready (101)"?
The answer to your question is that the difference between these two codes (100 and 101) is not publicly documented by apple.

https://discussions.apple.com/message/23429422?ac_cid=op123456#23429422

However pondini.org/TM/D2.html gives reasons why and how to fix those errors, and the issues you are experiencing.