BILLS --> INVOICES
BILLINGS --> TIME ENTRIES
Bills have been renamed to Invoices and Billings have been renamed to Time Entries.
These changes may be small, nothing moved, and no functionality changed with it, but we know these changes make things better because it just makes more sense. And when a product is more intuitive, it is easier to use.
We've actually got a couple more upcoming name changes as well. We'll continue to make things better and we want your feedback helping us to things right.