That's an extremely fine line to make though. What distinguishes an "event" from a "scenario"? Aren't they pretty much synonymous?
The PC's are in a city. There is a festival in the city. People are partying in the street. An enemy of the PC's uses the distraction of the festival to attack the PC's as they enjoy the festival.
Railroad or not? Event or scenario? Scenario or adventure?
The PCs are free to do as they want? Then the festival is an event, the assassins are an encounter at the event. Both the event and the encounter are part of a scenario.
Railroad version: GM: You are at the dunking booth, dunking witches when...
PC: Wait - why would I be at the dunking booth dunking witches? I
like witches!
GM: I
said 'You
ARE at the dunking booth, and you
ARE Dunking witches, when....'
PC: No, I am
NOT! You Silly GM person.
GM: The scenario says you are, so you are....
PC: I am going to go play with my Wii, you have fun running my character for me....
Other PCs: You have a Wii? Can we play? Gotta be more fun than dunking witches....
I mean, we're splitting some serious hairs here. RC is trying to claim that adventure is what happens AFTER play, but scenario is what's created before play. That's a new one to me. I've seen both used pretty interchangeably in the past. Module, scenario, adventure... do we really need to make distinctions here?
For me it is a major difference in the use of terms - It is a hair as big around as a sequoia, and if you can't make out the difference then I may need to hit you with a hammer. A Nerf hammer, but a hammer nonetheless.
An event is what is going on. The festival will be happening, whether the PCs are there or not.
A fire is an event. It is going on whether or not the PCs are there, unless of course they are the ones who set the fire, or the fire was set because the PCs are there. It will still be an event even if the PCs are the cause/reason for the fire. Things are going on.
San Fransisco
did have a great quake - it would still have the quake, even if the PCs are in Boston, listening to the church bells ring. It is an event - things are happening. Fires did level much of the city in the aftermath of the great quake. The fires will still happen, even if the PCs are in Boston, sitting in the church, sending alms to help the people displaced by the eruption of Mt. Vesuvius. The fires are an event subsequent to the great quake. The gathering of alms is an event that is taking place con-temporally with the fire in San Fransisco, and would be taking place whether or not San Fransisco got flattened then burst into flames.
At the festival the PCs are attacked by a bunch of goons, sent by the bad guy. The attack is an encounter at the event. The GM has both the festival and the attack in an adventure - adventure is, for this usage, synonymous with scenario.
At the church in Boston the PCs meet up with a kindly vicar who tells them that he feels that something terrible has just happened, but that he is not certain of what. Meeting the vicar is an encounter at that event. As it happens the volcano, the earthquake, and the fire have nothing to do with the scenario - the GM has just noticed the game date, and felt like adding some flavor. The important part is the meeting with the vicar, who will be important later in the scenario.
Personally, I take railroading to mean the DM has taken away player agency in such a way that the player objects. I mean, if the DM says, "I'm going to let a month pass, any objections?" and no one objects, that's not railroading, despite the fact that he just took away player agency. However, if the DM says, "One month passes" and ignores the players wishes entirely, that is railroading.
And no argument there. (What? You thought I was going to disagree with you?) It is close enough to my own definition of railroading that I can live with it - I might add that for me it would really become railroading only after the same thing happens repeatedly, but that is just an argument over how many, not kind.
I'm a huge fan of aggressive scene framing. Glossing over small details to get to the big stuff. Not to everyone's taste, certainly, but, something I do appreciate in a game. I don't enjoy the book keeping that goes along with highly detailed exploration style games.
Am I being railroaded? I don't think so. I've accepted that details will be glossed over and trust my GM will bring the fun to the table. If you play with a GM you trust, you don't have to worry quite so much about losing a little player agency once in a while.
It doesn't sound like railroading to me, either. Now if the GM was dragging your character from place to place, event after event, encounter after encounter, then I think both of us would agree that it is railroading.
Rather a long winded means of basically just saying 'I agree', wasn't it?

I mostly just wanted to clarify my terms, for my own usage. My only real disagreement was calling it splitting hairs, since to me the distinction seemed obvious.
The Auld Grump