That's actually the truth.
Samsung's component unit can make more money selling the best components to Apple instead of using those components for their own smartphones/tablets.
The only exception is the AMOLED PLUS screen, because they can only produce a small amount, it's of no use to Apple, so they use that for their own Galaxy phones.
As someone mentioned, it's different businesses for starters. You're talking a huge manufacturing activity that produces all kinds of electronic components, compared with Samsung Mobile, which faces all the challenges that even Nokia, Microsoft, Moto, etc. are stumbling over.
AFAIK Samsung has been strong on the manufacturing side for a much longer time before deciding on producing their own wide range of mobile devices.
They've always had a good run with screens, in the late 90's I had my nice Samsung Syncmaster 15" CRT. Quite decent. Now I have a 21" flat panel version, more than 10 years later.
Samsung knows screens... The LG plasma and LCD flat panels of the past few years never seemed to have impressed me. Recently at home we went with a 46" 1080p LED-backlit Samsung HDTV. Not too bad so far.
Will they keep up the quality? We shall see.