Spanish guitar is a loose term which people use to refer to any acoustic guitar music with a Spanish sound. Flamenco is the folk music of a particular region of Spain which is often confused with classical guitar because they both involve a guy in a suit playing a guitar with his fingernails. Flamenco has little in common with classical guitar because it is basically just the guitar accompaniment to Flamenco singing and dancing with guitar solos being a late development in this genre.
Classical guitar which is classical music played on a nylon string acoustic guitar with no cutaway at the top frets. The guitar is usually made from Rosewood for the sides and back, and Cedar and Spruce for the front.
Classical guitar is strongly associated with Spanish composers from several different periods of history and the prime mover of classical guitar technique was a Spaniard by the name of Andres Segovia.
Here is a video of a simple classical guitar piece called Espanoleta . . .
One of the attractions of Spanish guitar is that it is just the guitar and you. No equipment other than your instrument is required, and the music you produce is the result of your practice. Whatever your definition of Spanish guitar music, there are lots of pieces that have been published and are within the reach of the dedicated amateur acoustic guitar player. This means if you work reasonably hard you will have a half-hour or so repertoire in a few months. Once you get to that stage you will be quite a formidable Spanish guitar player.
Thanks to the internet almost any kind of music you could think of is available in the form of guitar tabs. If you are going to put yourself through the rigor of a disciplined guitar practice routine, you should think about going the extra yard and learning to read sheet music. For classical or Flamenco music you are going to need to read music or have one of the guitar tab software programs that allow you to hear the MIDI files of the piece you are studying. Learning to read music might seem a bit daunting but all in all it will work out the easier course in the long run.
Spanish guitar is one genre where you really need to take lessons from a live teacher. The trouble is you might have to travel to another area to learn it. If time and budget do not allow you to take lessons, buy a copy of the book, Solo Guitar Playing by Fred Noad. It has all the basics you need to learn plus pieces you can learn as your technique progresses. Also remember to keep an eye on the video websites for any lessons in Spanish guitar you can get.
Another book of Spanish guitar music you should look for is A New Tune A Day For Classical Guitar. It has pieces from the classical guitar heavyweights like Sor, Bach, Carulli and Carcassi plus some other tunes like Scarborough Fair and Amazing Grace.
One of the good things about Flamenco guitar music is the chords are easy to learn and sound great so here is a lesson that will show you some chords that will turn you from a newbie to a guitar player . . .