Here’s the breakdown: Voice is your own. It’s a developed way of writing that sets you apart from other writers (hopefully). It’s your personality coming through on the page, by your language use and word choice. When you read a Dave Barry column, you know it’s his. Why? He’s developed a distinct writing voice.
Style is much broader than voice. Some writers have a writing style that’s very ornate—long, complex and beautiful sentences, packed with metaphors and imagery (think Frank McCourt and John Irving). Others have a more straightforward style—sparse prose, simple sentences, etc.
Here’s one way to think about it: WD tries to have all its articles fit a similar style—conversational yet straightforward. But between the covers, each piece is written by a different author whose own voice colors his particular piece. So the continuity of the magazine stays together, but each piece is still different.