English for Writing Research Papers

6.13   both … and, either … or
both … and
 is inclusive. either … or is exclusive.
 
S1.  We studied both English and Spanish.
 
S2.  You can study either English or Spanish.
S1 means that we studied English and we studied Spanish. S2 means that you can 
only  study  one  language.  You  cannot  study  English  and  Spanish.  You  can  study 
English or you can study Spanish.
 
S3.  You cannot study both Russian and Korean.
 
S4.  You cannot study either Russian or Korean.
S3 means that you have to choose between Russian and Korean. You can only study 
one  of  the  two  languages.  S4  means  that  these  two  languages  are  not  offered. 
Neither of them can be studied.

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102
6 Avoiding Ambiguity and Vagueness
The position of both can change the meaning. Note the difference between these 
two sentences:
 
S5.  This is true both for the students and the professors.
 
S6.  This is true for both the students and the professors.
In S5 there are several students (and professors) involved, in S6 there are only two 
students and an undefined number of professors.
In S7 just two parks are being referred to, whereas in S8 there is an unknown num-
ber of parks.
 
S7.  We had fun in both the parks we visited and also the museums.
 
S8.  We had fun both in the parks and the museums.