Socks on Jermy Street

Is there any quality difference between the different traditional jermyn street shops when it comes to socks, or is it just a matter of different profit margins and different selection?

Take Harvie&Hudson vs. Turnbull&Asser for example. £17 vs $24 a pair, is there a difference, or are they the same ones manufactured by Pantharella or whomever?

That's awesome, do you know if they deduct VAT from their prices if you order them sent to an offshore address?