It's fun to read various forums where people discuss what kind of approach they take to being a DM. There's more variety than you may realize.
The "Conflict" DM: These folks really get into building conflict for the PC's. There is often a lot of roleplay involved in their games as the NPC's roleplayed by the D are not going to give just a simple reply to PC questions. NPC will be argumentative, disagreeable, confrontational and anything else that will elicit a reaction from the PC's. Adventuring itself may sometimes take a back seat to roleplaying with DM's like this.
The "Divine" DM: Many times, these DM's are called "railroaders.". The DM in this case will have the game they want to play, regardless of the Players interest or willingness. Go left, there's the hook. Go right, there's the hook. Go forward, yep, same hook.
The "Confrontational" DM: These folks are all about pitting their adventure building skills against the players. The old "DM vs Players" type. It's not just wanting to see how well Players do against the adventure they made, it's personal, almost like a vendetta. A TPK is like giving this DM a gold cup or a blue ribbon.
The "It is what it is" DM: This DM really has no interest in personally challenging the players like above. For them, the game is everything. They couldn't care less if players fail or succeed in an adventure, it's more about, "How cool was that?" for this DM. Originality is an important thing for these people.
There are other types or maybe sub types and undoubtedly combinations of these. I there's something to be learned from all of them and each of them can provide a good experience for the right type of Players.