I've read the novels from the start up until recently, but never actually played the game, even though I have two of the game books. I'll go with the 3rd edition Dragonlance Campaign Setting book I have here.
1-Magic, it depends on what time period you play in within the game world. Older time periods have high magic, then very low, then low-medium, then to present when it went back to average which is what's presented in the book.
2-The information presented on geography, they give color maps, short descriptions of important towns/regions and important NPC's. They provide about a page or so on descriptions of each important town, along with such things as general population, government composition, trade, languages and alignments found in the area.
3-It's different, since I haven't actually played either, I can't say too well. However I can say, in some ways the way they wrote it, they made certain things restricted as a flavor type thing. For example, the Towers of High Sorcery. If your a wizard or sorcerer, and wish to use high level magic you had to join up, or become a renegade and be hunted down. This required passing a lethal test and if you passed you joined in, if not you died. Now they've added different classes to represent when deities dissapeared and mortals found their own way with things and such. It's got it's own little world apart from the FR. I personally find it more to my liking because it IS written in certain ways to add more flavor without simply granting power to add that flavor.
4-
a. Different Knightly Orders to join and progress in. Somewhat encompassing your Blackguard, CoT, Paladin, and Fighter classes, but in a different manner and with a definate background, history and feel to them.
b. High Sorcery orders. White, Red and Black Robes all encompass different alignments, work together on some issues, and struggle for power against each other as well. Arcane magic ends up becoming a political struggle at the higher ranks within the group. Otherwise, you end up being a renegade and being hunted, or joining with the new group of Mystics, which encompass almost a mix of sorcery type spell casting (as in innate) but blending clerical and wizardry type effects together.
c. Certain races have been written to encompass stereotypes which give them a distinct feel. Gnomes suddenly all are scientist/inventers and those that aren't are seen as "mad" and leave to wander on their own. Halflings are now Kender and immune to fear and have different abilities. Draconians were spawned from dark sorcery and the eggs of good dragons, creating a new, powerful race. The Irda, another race, the 1st ogres, who are good, isolationist and magical beings, before ogres were corrupted. Humans have been set apart and there are civilized stats and barbarian stats for human. Dwarves now have the "Gully Dwarf" subrace. Frightened, disgusting dwarves that make great thieves and comic characters.
High level campaigns can enter into dragon riding with dragon lances and there's a history of deities usurping power and trying to conquer the world through meddling with dragons and such.
You can wander outside the main continent and head to the south pole of the world to find a land of ice and a totally different setting with ogres, humans and thanoi constantly fighting and struggling for survival against brutal winter storms.
Hope that helps.
