When you take a close look at the various trailers of Mass Effect: Andromeda, you'd be forgiven for getting the impression that the game at least offers some kind of open-world with a focus on player freedom. However, Bioware thinks that you/we should probably refrain from calling it an open-world, though, because according to them, the game exists somewhere in between, something open and at the same time linear.
Recently, producer Michael Gamble had a chat with Official Xbox Magazine (via Gamesradar), and here he said that they prefer to refer to the game as "exploration-based", rather than open-world:
"I definitely wouldn't call Andromeda an open-world game. We like to use the term 'exploration-based game.' You still have the concept of tight story deliverance and all the great things you come to expect with Mass Effect.
"The layer on top of that is a layer of exploration. Sometimes that happens in open spaces, but not always. You can cruise around some of these planets in the Nomad, but it's not the traditional sandbox-type game."