Physical appearance.
SOME strains of Egyptians tend to be finer-boned and dishier
SOME strains of Egyptians are bigger, raw-boned but still dishy
Polish tend to be tall, athletic, bigger boned and less typy
Russians are like Polish only usually leaner
Spanish tend to be smaller, a little more compact
Crabbet look a but like Egyptian, a bit like Polish. Typically with shorter necks and rounder hindquarters
CMK look a lot like Crabbet but more variation
Current domestic strains are going 1 of 3 ways.
Halter horses are beginning to look like deer: skinny, big eyes, kinda useless for riding
Show horses are tending to look like Saddlebreds
Sport horses are tending to look like Warmbloods with nice heads
Only distance/endurance horses seem to realy be retaining Arabian build and type