Why AWK print is strange when I set FS = " " instead of FS = "\t"? - awk

Question

Look at the following data file（cou.data） which has four fields separated by tab.
Four fields are:
country name
land area
population
continent
As for country name or continent name which has two words, two words are separated by space.
(Data are not accurately confirmed, just for test purpose)
USSR 8649 275 Asia
Cananda 3852 25 North America
China 3705 1032 Asia
USA 3615 237 North America
Brazil 3286 134 South America
India 1267 746 Asia
Mexico 762 78 North America
France 211 55 Europe
Japan 144 120 Asia
Germany 96 61 Europe
England 94 56 Europe
Taiwan 55 144 Asia
North Korea 44 2134 Asia
awk 'BEGIN { FS = "\t" } { print $1, "---", $4 }' cou.data
I got the output which exactly meets my anticipation:
USSR --- Asia
Cananda --- North America
China --- Asia
USA --- North America
Brazil --- South America
India --- Asia
Mexico --- North America
France --- Europe
Japan --- Asia
Germany --- Europe
England --- Europe
Taiwan --- Asia
North Korea --- Asia
Then I replace \t by one space (" ")
That is :
awk 'BEGIN { FS = " " } { print $1, "---", $4 }' cou.data
The output I got is not understandable to me
USSR --- Asia
Cananda --- North
China --- Asia
USA --- North
Brazil --- South
India --- Asia
Mexico --- North
France --- Europe
Japan --- Asia
Germany --- Europe
England --- Europe
Taiwan --- Asia
North --- 2134
Line 2,4,5,7,13 each have one space and the other lines have no space(s) at all.
As for lines that have no space, why $1, $4 still can be printed ?
As for line 2,4,5,7,13, I thought $1 should be printed like this:
Cananda 3852 25 North
USA 3615 237 North
Brazil 3286 134 South
Mexico 762 78 North
North
And $4 does not exist.
Where did I get wrong ?

Answer 1

So problem here is string/country names on 1st field which are having spaces in their names for example North Korea. So when you are setting FS as \t this string will be considered as a single field on the other hand when you will set FS as space this will be considered as 2 different fields. That is why you are seeing difference between field numbers after changing the FS values in your codes.
I would suggest your first attempt is good enough to get your expected values.