Both the web and the mobile version of the Family History Tool sync seamlessly (when connected to wifi) so you can access the same information on both your iPad and your computer.
The information in the Family History Tool is stored in the cloud, so both versions of the application work with the same data. A single account is used to work in the web app and in the iPad app. All of your account's data is available from anywhere. Please keep in mind that if you are using the iPad app in offline mode, you need to go online for the changes to be synced.