Missions or Quest confusion...

Been playing GW for a few weeks now and also looking around on this forum. One thing that I'm not too sure about is:

1) What defines a "mission"?

2) What defines a "quest"?

I'm wandering around in post searing at the mo, in the general area of Old Ascalon, Sanitarium, Piken (?) Square etc and I have met loads of NPC's with the green "!" above their head who give me things to do. Are they missions or quests? How do I tell the difference?

From readiung around, there is obviously a story line with specific missions which give you useful stuff but at the moment I just feel I'm wandering around a bit aimlessly, a bit like an odd-job man

Bit worried I might miss something crucial to the story....

When you see the icon "Enter Mission" appear below your party screen window, thats a mission. Quests will appear in your Quest Log (default "L" button).

Quests are optional, missions are quests which needed to be done to progress in the game, for the storyline.

Quests - little things to do for NPCs just for rewards and Xp.

Mission - bigger quests for Xp and advance the main storyline.

In the Quest Log (keypress "L"), the mission quests appear at the top of the Quest Log. Within mission quests there are also hidden bonus secondary missions for extra Xp. It's 1000Xp for mission and an additional 1000Xp for doing the bonus.

You can tell that you're in a mission start point as other players will have their profession and level displayed above them. Team leaders will indicate the size of their current party. The party window will also have an "Enter Mission" button.

Thanks all...that's cleared things up a bit for me I was wondering why I came into one area and everyone had their profession/lvl in blue above their heads rather than names....

If you look at your big map, the places with a shield will have a mission. After you complete the mission a sword will go through the shield, if you also complete the secondary mission, another sword will cross the other through your shield.

Ah....that answers another question I had been wondering about!