Updating Peakto after making changes in Lightroom

Updating Peakto after making changes in Lightroom

Hello,  Trying to find the best way to update Peakto with Lightroom catalog when changes to ratings, keywords etc have been made.  

Where can I find the answer to the difference between
Smart Re-ingest 
Synchronize now
Custom Sync
Compute Missing AI scores
Run Image analysis

Thank you in advance,