At the end of my review of Wingspan, I mentioned that I'd rather play Azul. Discussion under that post helped me clarify what, in particular, I prefer. Both games play primarily on individual player's game boards and look fantastic, but beyond that they diverge considerably in instructive ways.
Whether you prefer ornithology to Portuguese tile is really the only way to separate these games as aesthetic objects. Just as the bird cards in Wingspan resemble historical bird illustrations, Azul's resin tiles look very much like azulejos from Lisbon. It is a shame, however, that two "patterns" are simply blue and red. This can be rectified by purchasing "collector's tiles" from Next Move Games. I'm not sure how I feel about that except that it does no harm to the game unless you can't tell the tiles apart without a distinct pattern.
I won't go into the score or tile-laying rules except to say that they are surprisingly deep and you almost always need a precise number of a particular tile to score without losing points to "broken" tiles. (The more excess tiles you fail to place, the more points you lose per tile.) What makes Azul exceptional is the tile drafting system.
Each round begins with a number of display circles scaled to the number of players (5 for 2 players up to 9 for 4). Each display circle is filled with 4 randomly-drawn tiles. Players take turns choosing one color from a display. They must take all the tiles of that color from the display and the other tiles are moved to the center display. Players can also draw all of one color from the center display, but the first player to do so incurs a minor penalty. Once all the tiles are removed from the displays (including the center), the round is over.
As you plan your round, you might expect to draw, say, 2 red tiles from a particular display. But if another player takes those tiles first, you might need to take 1 red tile from two displays over two turns, which amounts to an opportunity cost. Or, you might decide to dump the red tiles into the center by picking other colors that help your strategy. Critically, plans can be disrupted by players who have no interest in the color you want since they might dump your color into the center with more tiles than you need. Or you might get a windfall as another player unexpectedly gives you just the right number of a pattern by taking other tiles you don't care about this round.
It's harder to explain than to experience, but the drafting system means every other player is doing something potentially interesting (to you) on their turn. Once one person draws their tiles, the rest of the table can draft tiles as they set them down on their tableau. As a result, there's no real downtime as long as people are quick about planning. Even if someone else takes longer to plan, there are always moves and strategies to consider for yourself since the only randomness occurs during the round setup.
Compare that to Wingspan where both birds and food are drafted from a common pool. But unlike drafting in Azul, the Wingspan design blunts the effects of other players by adding mitigating mechanics. Instead of being stuck with just one unwanted choice of food, players can reroll to get a new set of choices. Or you can convert two food tokens into any one food of your choice. Or you can aquire a bird power that lets you convert food. Or you can just do something else and wait for the right food die to come up.
The bird pool has different mechanics, but similar mitigations. If you know what bird power you want and if that power turns up among the three visible cards, other people can mess up your strategy there. But that's somewhat rare compared to the way other people drafting Azul tiles impacts your plans just about every turn. It's the difference between feeling like you are playing with other players and feeling like other players occasionally impact your game.
Azul isn't perfect. Since all the information is open to players at the start of each round, there's a possibility of decision paralysis. Depending on your temperament, the opportunity to screw over other players could be a negative. Wingspan works pretty hard to avoid overt negative interactions. The cost is these can sometimes be underwhelming. Nearly everything in Azul changes the game in meaningful ways, so it can also be more confrontational.
With my children, who don't yet have the skill to be competitive, I've stopped worrying about keeping score. It's not as if I take particular pleasure in beating them anyway. Instead we work to build our walls, which is perfectly satisfying. Alternatively, it works to score people who want to compete and not score those who don't. I suppose this works for any scoring game, but I only just discovered the technique with Azul.
I like that Wingspan sets random bonus goals so that each game is different. I like even better that Azul has goals that are carefully balanced. Lucking into extra points because you happened to have cards that work for the preset goals feels less rewarding than achieving a bonus that you know from prior experience is difficult to do.
Azul simply has the opposite philosophy when it comes to design. I wouldn't exactly call it minimalist since the game feels rich with possibility. But I would say it's weighty where Wingspan feels flighty. Perhaps it comes down to a difference in preference of theme after all.