Lead Sheet:

What is a lead sheet?:

A lead sheet is very similar to a chord chart. It outlines the chords, key and time signature like a chord chart. But also includes key melodic sections, lyrics and harmony and is often more instrument specific. 

A lead sheet is often also called a fake sheet and is designed so a group of musicians can use it to 'fake' playing a song without access to the full arrangement. A famous collection of lead sheets for jazz standards is 'The Real Book' and it contained the basic musical information a musician would need to perform and improvise over jazz standards.