What is deploy conflict: module field(s) is more than the length of the mapped fields in the production account.

What is deploy conflict: module field(s) is more than the length of the mapped fields in the production account.

Hello

I am trying to deploy changes to our Quotes module from a Sandbox to Production and my subform is erroring with "module field(s) is more than the length of the mapped fields in the production account" 

We can't figure out what is causing this error. We also did the same changes to Sales Orders and that one doesn't seem to be conflicting. 

Help would be much appreciated - thank you!