Good Question! Here are my thoughts...
I myself don't really use the phrase Pocket Pussy. This is a generalized term, but if a masturbation sleeve is designed to look like an anus, a mouth, a flower, a can of beer, or something non-descript, then it would not really be a 'pussy'. Blow Job imitators are usually a masturbation sleeve with a mouth entrance. So, I guess according to this logic all pocket pussies are masturbation sleeves, but not all masturbation sleeves are pocket pussies.