To expand, Legend Lore was/is just a more powerful way to pierce more closely guarded GM secrets. You're still asking the GM to tell you what's in his notes, which may be "nothing".
Spout Lore obliges the GM to tell you something relevant and useful in accordance with what you ask.
The difference is pretty big in use. Legend lore gets gets at more of the GM's fiction, while Spout Lore obliges the GM to create fiction in accordance with your question.
People are claiming I don't understand stuff, and in this case it's true.
First off, can we agree that the following two steps are valid
Step 1 - player-as-PC declares Spout Lore; or her Bard uses Legend Lore; or does whatever the system-in-use equivalent may be, if such exists; in order to gather some info
Step 2 - on success, the GM in response provides some new information centered around whatever it is the PC is inquiring about.
Are we good so far? Excellent.
Now here's what I don't understand:
why does it matter where that new information comes from or how it is generated?
Put another way, ignoring the root source and looking only at the info gleaned, from the player's side what's the difference? (consider, say, an online-play context where you can't physically see the GM and thus have no way of knowing whether the new info comes from prepped notes or from spur-of-the-moment - how are you-as-player ever going to know the difference?)
Let's say I'm a player in a game, and we've just by whatever means found what we think might be the long-lost Statue of Adonis*. We're not sure if it's the real one, however, all we know is that the real one was made by the famous sculptor Agrippa Kimenestra and it's rumoured that some fake copies were made later. So someone uses an info-gathering ability (along the lines of Spout Lore, Legend Lore, a knowledge or artistry check, etc.) to try to determine who made this statue we've found. The ability/check succeeds and we learn that
yes indeed this statue is an authentic Kimenestra work.
From my perspective as a player, and ignoring anything the GM does other than the words she speaks, what difference can it possibly make to me whether the source of this info is the GM's notes or spur-of-the-moment improvising or something else?
* - recovering the real statue could be a stated goal for a PC or a mission goal for a party or whatever - all that matters for this purpose is that for some reason we're looking for it. (or maybe we've stumbled onto it while doing something else entirely?)