[treis]

Your examples aren't really doing the same thing in two different ways. Map (and select, collect, each, and some others) iterate over an enumerable. Pluck and select are active record methods that generate SQL.

It's a good example of choosing magic/brevity over expressiveness. You don't know that Tag.all.map calls SQL because it's not something you explicitly tell it to do. That's the real issue with Ruby & Rails. The magic lets you do some powerful stuff but sometimes it's hard to tell what exactly is happening.

[joshmn]

That's why I said they produce the same result instead of saying they do the same thing. If you read further in my example, I mention that they perform very differently under the hood.