Size: Pocket trumpets are smaller than B-flat trumpets. They have a shorter length and a smaller bell, which makes them more portable.
Pitch: Pocket trumpets are pitched in B-flat, just like B-flat trumpets. However, they sound an octave higher than B-flat trumpets, because they are shorter.
Tone: Pocket trumpets have a brighter, more piercing sound than B-flat trumpets. This is because they have a shorter air column, which creates a higher-pitched sound.
Usage: Pocket trumpets are often used in jazz and other types of music where a more portable instrument is needed. They are also popular for use by children and beginners, because they are easier to play than B-flat trumpets.
In conclusion, pocket trumpets and B-flat trumpets are both brass instruments that are pitched in B-flat. However, they have different sizes, pitches, tones, and uses.