While one is far bigger than the other, there are two waves in free agency. The first comes as the new league year opens, and is when the vast majority of the biggest free agents on the market sign their deals. This also includes significant trades being made. Even the Pittsburgh Steelers got in on that last year when they traded Antonio Brown.
The second wave comes after the draft, and in the case of this year and going forward, it’s now almost immediately after the draft—the first business day. Under the new CBA, the compensatory deadline is the Monday after the draft.