Rowers, kayakers, and canoers all have some things in common. They utilize a conveyance on water, they mechanically propel themselves on the water, and wear life jackets. Just as they all have similarities, they also have several differences. They use different mechanisms to propel themselves, they sit different and execute different techniques to achieve their goal. You can take a good canoeist, put them in a kayak and they may be able to move around, but not nearly as efficiently or cleanly as the kayaker.
The very same can be said of guitarists. Every style of guitar has their unique differences, and it would be pretty extreme to expect any one style to pick up another and rock it. This is one of the expectations that beginning classical guitarists have more often than not. This is even more difficult if they are self taught in the other style of guitar. Early on, I was told to be aware of the differences between classical and electric styles as it was more difficult as a guitarist to learn both. Luckily, I had a teacher that played both, who learned from a teacher who played both, and they both did it extremely well. I can’t say that I do the same, but I managed my lessons just fine transitioning between the two. What I can say is there was a significant transition from one to the other. The entire feel of the instrument was different and I had to make an effort to change technique from one to the other. Beyond that though there are other significant factors that have to be taken into account.
1- Moving from a pick, to a classical right hand. Pick playing utilizes short fast alternate picking with contact on either side of the plectrum over the strings. For strumming rhythms, the whole hand and arm is utilized for the rhythm. Often, the guitarists hand is very close to the strings and body of the guitar, and the palm is involved for additional muting effects. For classical guitar, the right hand is more stable with minimal movement when playing. The right hand is also held above the strings with no contact to the guitar body. Instead of alternate picking, classical guitar uses alternate fingers, generally with more follow through than a pick, and also contact is made on the same side of the string, playing in one direction as opposed to the up / down playing of a pick over the string.
2- Left hand for many styles of guitar use a more laid back hand, with the knuckle of the first finger locked or resting on the neck of the guitar. This facilitates a fulcrum point for initiating string bending. Because the electric and steel string acoustic guitars usually have strings that are closer together, finger groupings are more smooshed together. This hand position easily facilitates this. It was recently demonstrated to me by Dave Grandel of String Theory Guitar Academy how he used one finger to fret two notes by placing his finger straight down between the strings! I was very impressed. Classical guitar strings however, are spaced further apart, as are the frets due to the nature of nylon strings. This allows the intricate left hand fingerings and movement in classical guitar.
3- Seating position for classical guitar is generally not comfortable for other style players. Generally other styles will usually have the guitar resting on their right thigh while sitting back ( or forward ) when they play. In this position, they can comfortably play sitting on couches, sides of beds, cross-legged on the floor, on a bench, or just about any where they would want to set and play. Classical guitar requires a very formal position for proper execution which has the guitar resting on the left thigh which is elevated by a foot stool. Sure you can play sitting on the edge of a couch, or on the side of a bed, but it’s not recommended, and without that leg raised up, it’s much more difficult.
Given these differences, as well as the differing techniques, if a student has experience in another style of guitar, they must take care and expect a transitional learning curve when they pick up a classical guitar. Even though they may have a knowledge of the fret board and the notes on a guitar, they will have to take time to balance their left hand to the classical position.
Reading music is another issue. Most guitarists from other styles are used to reading chord charts, and music written out in tablature. A guitarist may know instantly how to play a C chord and recognize its variations from a chord chart, but when facing the same chord written on a staff, it will appear drastically different and take time to decipher.
These aspects of sight reading music, and adjusting to the position and techniques of classical guitar all take time to learn. For the experience guitarist, it may feel like starting all over again. The effort though is worth it if they stick to it. For once they begin to settle in to the classical technique, they will soon begin to become more comfortable and be able to apply their knowledge to their classical work. The key then is to adopt the patience of a beginner, to harness the experience they have achieved from their previous guitar experience.