Are there any two chinese words which can be used interchangeably?
Many Chinese words contain multiple meanings, in certain context, two different words that share an overlap meaning can be used interchangeably
Example:

正確 : accurate; correct

凖確 : accurate; exact; precise; spot on


Interchangeable case:

正確答案 = correct answer; accurate answer
凖確答案 = accurate answer
(both mean the same)

non-interchangeable case:

凖確射擊 = accurate shooting (accurately hit the target)
正確射擊 = correct shooting (shooting in a correct form)

More example:

教 : 1. (v) teach; instruct; educate; 2.(v) [colloquial] cause; make

授 : 1. (v) confer; award; give; grant; 2. (v) teach; instruct; lecture


Interchangeable case:

教他武功 = teach him martial art
授他武功 = teach him martial art
(both mean the same)
Although they are interchangeable when meaning 'teach' , 教 is more colloquial, 授 is more literary

non-interchangeable case:

教人難受 = cause people to feel bad (cannot be changed to 授人難受)
授以重任 = give important task (cannot be changed to 教以重任)