Classical Guitar
While the classical guitar is technically an “acoustic” guitar, they are different than what most people commonly recognize as an acoustic guitar. For one, they use nylon strings rather than the steel strings common to a true acoustic version. This tends to give them a much warmer, albeit softer sound.
The neck of a classical guitar tends to be slightly wider than its acoustic cousin. This could be, in part, because nylon strings tend to be wider than their steel counterparts, and therefore require a bit more space. It also helps to accommodate the intricate finger patterns that are common to the classical playing style.
It takes years of intense training to become a proficient classical guitar player. The style requires extreme finger dexterity and stamina, which can only be achieved through hours and hours of practice. Furthermore, the music that is typically composed for classical guitar is very complex.