What's the difference between fajitas, enchiladas and tacos? I'm not familiar with Mexican cuisine, but I enjoyed the things I've eaten so far. To me, they are all quite similar. Is there a real difference between fajitas, enchiladas and tacos?

The taco is perhaps most distinguishable, because of the hard shell, but I've seen pictures of soft tortillas as well. But fajitas and enchiladas are both rolled up meat + veggies + sauce in tortillas, no?

I've checked some websites and pictures, but I can't find a good criterion.

Is there a real difference? If so, what is it?
Enchiladas are normally shredded meat and/or cheese rolled in corn tortillas, covered in red (or green) enchilada sauce and cheese, and then baked.

Fajitas are normally strips of meat either grilled or sauteed (often with onions and peppers). They can be used in tacos, burritos, or served on their own or with tortillas on the side (corn or flour depending on preference). 

Tacos can be either hard or soft shelled and are usually meat (shredded, ground, grilled etc) with some sort of cold veggies (like lettuce, raw onions, pico de gallo, etc) and perhaps cheese etc.