Have the code run an Update Query that copies all the information from one table into the other one. If by 'intervals' you mean time intervals then it'll be a little annoying to set up, but you could always place the code that runs the query in the 'On Open' event of the first form that opens in the database so it synchronizes whenever you open things up.
If you need time intervals, perhaps have it in the 'On Timer' event of a form that is always open when using the database.
Line of code to use:
Docmd.OpenQuery "NameOfTheUpdateQuery"