java - What is the difference between queryvalue() and querynode()? -

when wrote line:

this.atputifnotnil("qwerttty", profile.queryvalue("qwertty"), profile); 

it throwing compile time error.
when changed querynode(), got rectified.

this.atputifnotnil("qwerttty", profile.querynode("qwertty"), profile); 

i want know difference between two.