tell me why

this is mob from ksa a computer tech. I have been working for a year in a computer workshop “maintenance”.All the product we have here not good I mean it stops working in a short time,low performance,and not working as well .My question is there a deffrent between the product outside here .
products;harddrives,cd-roms,mainborads,etc…
in the hope the get an anser
MOB