This new release should be regarded as an upgrade to the vault (the same as 2014 to 2015) not an update. Major changes to the Vault API means a full migration is needed after the install.
It should also be noted that some Vault Professional functionality has been removed:
Compare Bill of Materials
Item Package Service API’s
Item Rollback Lifecycle State Change
Restricting Item Lifecycle State Change to Change Orders
We recommend that you fully read the whats new information before committing to the upgrade.
It is also good practise to install any version upgrades, such as this, to a test environment prior to upgrading your production Vault. You will need to test how your workflow procedures and processes will be affected and understand any changes that may be required. Further user instruction may be necessary on the new version.