Bascially, there are 3 types of 6 string guitars ... Classical, Acoustic and Electric. All of these guitars are made for either right or left handed musicians. The difference between each of these guitars is the style of playing and the type of music they are traditionally used for.

This does not mean that you can only play one type of guitar for one style of music. For example, Classical guitars are also used for folk or country music as you may have noticed on TV.
Classical Guitar
As the name implies this guitar is used typically for classical music. The strings are made of nylon and are tied at the bridge since they do not have ball ends although there are nylon strings made with ball ends used on some acoustic guitars. Notice also that the neck does not have any position marks.

You use your fingers instead of a guitar pick which is why this type of guitar does not have a pick guard. You will need to grow and shape your fingernails on your right hand (left for left-handed guitarists). By using combinations of just the fingernail, the fleshy tip of your finger or both so you can generate different types of tone, brightness or warmth of the sound as you finger-pick.

Serious study of this instrument involves a great deal of technique such as mastering the "Segovia" technique for your picking hand.

Acoustic Guitar

The Acoustic guitar is one of the most popular types of guitars and has 6 steel strings although 12 string guitars are also available. Notice the presence of a 'Pick Guard' which protects the guitar's top from damage due to strumming with a guitar pick.

You can use either a guitar pick or your fingers to play. You will find this type of instrument in almost all styles of music. Acoustic-electric guitars have a pick-up built into them but they can be played with or without an amplifier. You can also add a pickup later if you wish.

Electric Guitar

The Electric guitar uses steel strings and is usually played with a guitar pick. It requires an amplifier and for family members concerned about the volume there is good news since most amplifiers now come with both a headphone jack, which cuts out the speaker when used and a CD input. This means your home musician can play along to their favourite songs on CD and they will be the only one who can hear anything (unless they aspire to sing along).

There are so many styles of electric guitars that the best way to discover them is to compare them at your music store. Every seasoned musician has their own preference so it is best that you get one that sounds good and feels comfortable to you. Watch out for the weird shaped ones (5 sided ones, etc.,.) that look cool as they may have everything you want until you find out you can only play it standing up since when you sit to play it slides down on you.

Electric guitars come in 6, 7 and 12 string versions as well as double-necks or more such as Jimmy Page's famous triple neck 12 & 6 string with mandolin.