What is the difference between perfect pitch and relative pitch?
Perfect pitch names notes with no reference; relative pitch names distances between notes. Relative pitch is the trainable one musicians rely on.
Perfect pitch: someone plays a note and you just know it is an F sharp, the way you know grass is green. Very rare.
Relative pitch: given any starting note, you can tell how far every other note is from it. That is what most great musicians actually use, and anyone can train it.
Perfect (absolute) pitch is naming or producing exact pitches with no reference note. It appears in a small fraction of people and is strongly tied to early-childhood exposure.
Relative pitch is judging notes by their distances: intervals, scale degrees, chord qualities. It transfers across keys, which is exactly what playing and transcribing require, and it responds well to training at any age.
The two are independent: plenty of possessors of perfect pitch still train relative skills, and world-class transcribers often have no absolute pitch at all.
Research places genuine absolute pitch far below one percent in general Western populations, higher among speakers of tonal languages and musicians trained young; a sensitive period in early childhood appears central, and full adult acquisition is rarely documented.
What adults demonstrably CAN build is precise pitch memory (anchoring a reference like A440 and deriving others) and finer discrimination, which covers most practical wishes behind "I want perfect pitch".
Functionally, music is relative: a song transposed two semitones is the same song. That is why pedagogy from solfege to jazz training centers on relative skills, and why this trainer does too.